Welcome to the official modding documentation by ViewApp for CityDriver! In this documentation, we will show you how to create your own modding project for CityDriver and add it to the game.

However, before we can get started, we must ensure we have the necessary tools. One of the most essential tools for modding CityDriver is the Unreal Engine. This software is required to load your own assets such as meshes, sounds and textures into the game in the correct file format unique to Unreal Engine.

Please make sure that you are using Unreal Engine 5.1 to mod the current version of CityDriver. You can download the engine here: https://www.unrealengine.com/en/download

Lua scripts are used to program logic. Please note that we cannot provide explanations on programming with Lua or creating 3D models in this documentation, and therefore require this knowledge to create a mod for CityDriver.

In case you want gather and exchange knowledge with the developers and the rest of the community, feel free to join us on our Discord: https://discord.gg/viewapp-community

The easiest way to create a new vehicle is first to copy an existing vehicle. Open the CityDriver installation directory. In the folder "CityDriver/Content/Paks/Vehicles" you will find both the player and AI vehicles. You shouldn't modify files in this folder though as your changes may get overwritten by updates of the game. All mods that you create can be placed in DOCUMENTS/ViewApp/CityDriver/Vehicles/ so for example DOCUMENTS/ViewApp/CityDriver/Vehicles/NewVehicleABC/

Select an existing player vehicle and make a copy of the corresponding folder and move it to the folder mentioned above. Give the copied folder a meaningful name (preferably the name of your vehicle) and open it. Open the file "data.json" with a text editor (e.g. Windows Editor, Notepad++, ...).

The first and most crucial step in the "data.json" is to assign a unique ID to the vehicle. To get an ID, open the following page: https://guidgenerator.com/online-guid-generator.aspx Uncheck "Hyphens" and click "Generate some GUIDs!". As a result, you will get a letter combination that you can use as an ID. Copy this letter combination to the clipboard. In the "data.json" search for the entries "id" and "selectedProfileId" and replace the existing letter combination for both with the new ID from the clipboard.

Within the entry "meta" you can enter various metadata:

To use your own assets in the game you have to import them into an Unreal Engine project and then export a package of your assets to have them loaded into the game. We created a project for you which includes a plugin with some tools to make things easier. You can download it from here: https://dl.viewapp.com/CityDriverModdingProject.zip

You can get going by opening the project using Unreal Engine 5.1 and importing your first assets. Make sure to only import assets into the plugin folder "MyCar1 Content" :

Make sure that any assets you use are located in this folder or else they won't be exported and won't load into the game.

When you are happy with the assets you imported click on the export button which you can find in the toolbar:


The export process requires a folder to be chosen. All modded vehicles should be placed into the DOCUMENTS/ViewApp/CityDriver/Vehicles folder. So you can go ahead and create a folder called "MyCar1" and select it in the dialogue. The assets will then be exported to the target folder and will be ready to load into the game at the next startup.

For animations, a skeleton must be present. The Skeletal Mesh should not contain any meshes, but only the corresponding bones. The following bones must be present and named exactly as such:


Furthermore, for each part of the vehicle that is to be animated (e.g. doors, steering wheel, buttons, ...) there must be a separate bone at the corresponding position. These bones can be named as desired.

Export the bones from your 3D software as an FBX file and import them into the Unreal Editor. Open the Skeletal Mesh. Under Asset Details->Physics->Physics Asset click on Create New Asset->Physics Asset. Choose a file name and location and click Save. In the next step, select the imported SkeletalMesh. In the next step enter 0.0 for "Min Bone Size" and click on "Create Asset". If you have done everything correctly, you should receive a corresponding PhysicsAsset. Make sure that this PhysicsAsset is linked in the SkeletalMesh as a PhysicsAsset.

To link the SkeletalMesh to the vehicle, first right-click on the SkeletalMesh in the Unreal Editor and select "Copy Reference". In the file "data.json" find the entry "skeletonReferencePath" and paste the copied reference there.

The chassis, the wheels and all parts of the vehicle that are to be animated independently of each other (e.g. doors, steering wheel, buttons, ...) must be available as separate meshes. Export these parts individually as FBX files and import them in the Unreal Editor.

Static meshes should be linked in the vehicle folder in the file "profiles/default.json". First, the chassis should be linked. Search for the entry "chassis". There are the following entries:

Next, the wheels can be entered. Each wheel has its own entry, which can have the following parameters:

All other meshes must be linked as attachments. The following parameters are relevant for an attachment:


There are additional attachment parameters, which will be explained in the appropriate section.

Certain attachments must be assigned a role in order to function correctly. Currently, there are the following roles:

Several camera views can be defined in the "data.json" under "cameras". Each camera view can have the following parameters:


If a parameter is omitted, a default value is used.

The engine is configured in the drive train under "engine" and has the following parameters. It should be noted that some parameters only have an effect on a specific engine type.


*E = Electric; C = Combustion

Some engine parameters must be set via curves. For this purpose, corresponding assets of the type "Float Curve" must be created in the Unreal Editor. These assets can be linked to the vehicle by right-clicking on the asset and selecting "Copy Reference". This reference can then be inserted in the data.json at the corresponding parameter.

All curve types are described below with an example curve:

X-axis: Engine speed in RPM

Y-axis: Engine torque in Nm

This curve contains the maximum torque of the engine as a function of the engine speed.

X-axis: Engine speed in RPM

Y-axis: Engine torque in Nm

This curve contains the torque of the engine when the accelerator pedal is released. Below idle speed the values should be positive, above idle speed they should be negative to simulate the engine braking effect. The further the values go into the negative range, the greater the engine braking effect. The transition between positive and negative values should ideally be right at idle speed.

X-axis: Engine speed in RPM

Y-axis: Engine torque in Nm

This curve indicates the torque of the engine when no fuel is injected or the engine is stalled. Accordingly, the curve should be negative over the entire course.

X-axis: Throttle position (0 to 1)

Y-axis: Fuel injection (0 to 1) for a combustion engine or engine power (-1 to 1) for an electric car.

This curve defines how the engine reacts to the position of the accelerator pedal. Especially when the accelerator pedal is in a low position, care should be taken to ensure that sufficient power is available so that the vehicle can start well without having to overcome a longer pedal travel. In an electric car, positive values mean acceleration and negative values mean recuperation.

If "useOnePedalDrivingThrottleResponse" is used, two separate ThrottleResponse curves must be defined for acceleration and recuperation. The transition between the two curves is calculated automatically using the values defined in "onePedalDrivingRecuperationMaxThrottlePosition" and "onePedalDrivingRecuperationMaxThrottlePositionAtSpeed".

X-axis: Engine speed in rpm

Y-axis: torque in Nm

If "useCustomRecuperationCurve" is true, this curve can be used to define the recuperation behaviour depending on the speed.

X-axis: Brake pedal position (0 to 1)

Y-axis: Recuperation strength (0 to 1)

With this curve, you can define how much the car recuperates depending on the brake pedal position.

X-axis: Engine speed

Y-axis: Efficiency (0 to 1)

This curve can be used to define how the efficiency of the engine behaves in relation to the engine speed. It is used to calculate the fuel consumption.

X-axis: Throttle position (0 to 1)

Y-axis: Efficiency (0 to 1)

This curve can be used to define how the efficiency of the engine behaves in relation to the throttle position. It is used to calculate the fuel consumption.

Continued in the next section.

The gearbox is configured in the drive train under "transmission" and has the following parameters. It should be noted that some parameters only have an effect on a certain gearbox type. In addition, the "default_ev_transmission" should only be combined with the "default_electric" engine and the "default_dualclutch_transmission" as well as the "default_manual_transmission" only with the "default_combustion" engine.

*E = default_ev_transmission, D = default_dualclutch_transmission, M = default_manual_transmission

Table is continued from the previous section due to character limit per section.
*EV = default_ev_transmission, DCT = default_dualclutch_transmission, M = default_manual_transmission

The parameter "forwardGears" is an array containing all forward gears of the transmission. A forward gear has the following parameters:


A ShiftingMode contains the shifting points for a gear (at which engine speed the next or previous gear is shifted). Any number of ShiftingModes can be defined. Which ShiftingMode is active is controlled by the vehicle script. However, it is important that all gears have the same number of shifting modes. A ShiftingMode consists of the following parameters:


X-axis: Throttle position (0 to 1)

Y-axis: Shift point shift (0 = normal shift point, 1 = kickdown shift point).

If "dynamicShiftPoints" is active, this curve can be used to define how the shift points are to be set depending on the accelerator pedal position. 0 means that the normal shift point is used, with 1 the kickdown shift point is used. For values in between, the shift point is interpolated accordingly.

X-axis: Clutch pedal position (0 to 1)

Y-axis: Clutch position (0 = clutch completely open, 1 = clutch completely closed)

This curve can be used to determine how the actual position of the clutch behaves in relation to the clutch pedal. This can be used, for example, to simulate a certain dead travel in the pedal.

Various assistance systems can be configured in the "data.json" under "AssistanceSystems".

The anti-lock braking system prevents the wheels from locking during heavy braking so that the steering ability is maintained.

The traction control system reduces drive wheel spin by reducing engine power.

The electronic stability control attempts to reduce understeer or oversteer by braking individual wheels.

Autohold causes the brake to remain active when the car is at a standstill so that the brake pedal can be released without the car rolling away.

The hill start assistant assists when starting uphill by not releasing the brake until sufficient engine power is available to start the vehicle.

Each lamp that is to be lit independently of other lamps must be assigned its own MaterialSlot. Lamps that are to light up at the same time and in the same colour can be assigned the same MaterialSlot. For example, it is possible to assign the same material to all turn signals on the right side of the vehicle, but not to the turn signals on both sides.

Furthermore, all lamps must be located in a mesh that is assigned to the vehicle as an attachment. They must not be on the chassis mesh. However, it is possible to combine lamps with other attachments in one mesh, e.g. lamps mounted on the boot lid can be on the same mesh as the boot lid itself.

The material that is assigned to a lamp must have a material parameter that can be used to control the brightness.

In order to control the lamps, it is necessary to assign names to the corresponding MaterialSlots. For this purpose, there is the attachment parameter "dynamicMaterialIndices". This is an array that contains corresponding assignments according to the following scheme:

"MaterialName": MaterialSlot

MaterialName stands for the name assigned to this MaterialSlot and MaterialSlot for the index of the material slot.


In order for the headlights to illuminate the surroundings, it is necessary to define corresponding light sources. For this purpose, there are the section "Lights" in the "default.json", which can contain any number of light sources. A light source first has a name and then consists of the following parameters:


Materials can be controlled in the vehicle script by calling setMaterialParameterScalar(Attachment, Material, Parameter, Value) for scalar parameters. Attachment is the name of the attachment, Material is the material name assigned in the attachment, Parameter is the name of the MaterialParameter to be controlled and Value is the value to which the MaterialParameter is to be set.


Vector parameters can be changed by calling setMaterialParameterVector(Attachment, Material, Parameter, ValueR, ValueG, ValueB, ValueA). The functionality is essentially the same as for scalar parameters, with the only difference that Value consists of 4 variables.


The brightness of light sources can be controlled by calling setLightIntensity(Name, Value) in the script. Name is the name of the light source in "default.json" and Value is the value to which the brightness should be set.

For rear view mirrors, a material must first be created in Unreal according to the following template:

Depending on how the mirrors are mapped in the 3D model, it may be necessary to enter either 1.0 or -1.0 for UTiling so that the mirrors are rendered "the right way round".

For each mirror present on the vehicle, a separate RenderTarget must be created in Unreal. The size of the RenderTarget should be set so that the aspect ratio matches the mirror mapping so that the mirror image is not distorted.

For each mirror, a separate Material Instance must be created with the previously created mirror material as the parent. The respective previously created RenderTarget is entered as the MaterialParameter "RenderTarget". The Material Instances created in this way must then be assigned to the respective mirror meshes as material.

Finally, the mirrors must be entered in the "default.json" for the respective attachments. For this purpose, there is the parameter "sceneCapture", which in turn has the following parameters:

Many aspects of the vehicle (e.g. lighting, animations, ...) can be controlled via scripts. Lua is used as the scripting language. Any number of scripts can be created as .lua files in the "scripts" subfolder of the vehicle folder.

The following functions can be created in the script and will be called by the game when certain events occur.

Called when the script is loaded

Called when the vehicle is spawned

Called when a button on the mouse, keyboard, steering wheel or gamepad for which a mapping exists is pressed or released.

Name: Name of the mapping

Type: Indicates whether the mapping is pressed or released. Possible values: BUTTON_PRESSED, BUTTON_RELEASED

Called every frame

Data: State of the vehicle

Called when an attachment is interacted with.

InteractionName: Name of the interaction

Secondary: Is true if it is the secondary interaction.

Pressed: Is true if the interaction key has been pressed and false if the interaction key has been released.

This function in the script is called whenever a display is interacted with.

DisplayName: Name of the display being interacted with.

AttachmentName: Name of the attachment to which the display is assigned. This distinction is important if there are displays in several attachments that have the same name.

Pressed: Is true if the interaction key was pressed and false if the interaction key was released.

CoordinateX: X-coordinate of the position in pixels where the display was clicked.

CoordinateY: Y-coordinate of the position in pixels where the display was clicked.

Called when an animation has finished playing.

AnimationId: Id of the played animation.

Called when the vehicle is initialised

Definition: Vehicle definition

Profile: Vehicle profile data

Engine: Engine definition

Transmission: Transmission definition

Called when the number of persons in the vehicle has changed.

NumOccupants: Number of persons

Used for communication between different scripts. Called when another script calls publish(LuaValue Topic, LuaValue Argument).

Topic: Topic

Argument: Data sent with the topic.

Called when a vehicle function is called in the cross menu.

Function: Name of the function

State: New state of the function

The following functions can be called from scripts. Functions for drawing displays and playing sounds are in separate chapters for clarity.

Since variables in Lua have no explicit data type and each function can be called with any data type, it is noted with each function which data types the function expects for correct functioning. "LuaValue" means that the function accepts any data type for this variable

This function can be used to apply a rotation animation to a bone.

BoneName: Name of the bone

FunktionType: Type of animation function. Possible values: AINM_LINEAR, ANIM_CUBIC, ANIM_EASE_IN, ANIM_EASE_OUT

From: Start rotation

To: Target rotation

Duration: Animation duration

InitialDelay: Delay before the animation is played. If this value is 0 or omitted, the animation starts immediately.

This function can be used to apply a location animation to a bone.

BoneName: Name of the bone

FunktionType: Type of animation function. Possible values: AINM_LINEAR, ANIM_CUBIC, ANIM_EASE_IN, ANIM_EASE_OUT

From: Start rotation

To: Target rotation

Duration: Animation duration

InitialDelay: Delay before the animation is played. If this value is 0 or omitted, the animation starts immediately.

This function sets the rotation of a bone directly.

BoneName: Name of the bone

X: X-coordinate of the new rotation

Y: Y-coordinate of the new rotation

Z: Z-coordinate of the new rotation

This function sets the position of a bone directly.

BoneName: Name of the bone

X: X-coordinate of the new position

Y: Y-coordinate of the new position

Z: Z-coordinate of the new position

This function sets the position and rotation of a bone directly.

BoneName: Name of the bone

LocationX: X-coordinate of the new position

LocationY: Y-coordinate of the new position

LocationZ: Z-coordinate of the new position

RotationX: X-coordinate of the new rotation

RotationY: Y-coordinate of the new rotation

RotationZ: Z-coordinate of the new rotation

With this function, a script can save data which is also retained in a SaveGame. The corresponding key must first be initialised with initializeData.

Key: Name under which the data is saved.

Value: Data to be saved. Possible data types: Bool, Int, Number, String

This function can be used to initialise fields for saving data.

Key: Name under which the data is saved.

Value: Initial value. Is only set if the field does not yet exist. Possible data types: Bool, Int, Number, String

This function can be used to retrieve stored data.

Key: Name under which the data was saved.

With this function stored data of the type Boolean can be inverted.

Key: Name under which the data was saved.

This function can be used to query whether data has been saved using this key.

Key: Name under which the data was saved.

With this function, a scalar material parameter can be set. The prerequisite is that the material has been registered in the attachment using the parameter dynamicMaterialIndices.

AttachmentName: Name of the attachment

MaterialName: Name of the material as entered under dynamicMaterialIndices.

ParameterName: Name of the material parameter

NewValue: Value to which the parameter is set.

Continued in the next section.

Continued from the previous section.

With this function, a vector material parameter can be set. The prerequisite is that the material has been registered in the attachment using the parameter dynamicMaterialIndices.

AttachmentName: Name of the attachment

MaterialName: Name of the material as entered under dynamicMaterialIndices.

ParameterName: Name of the material parameter

NewValueR: R-component of the parameter

NewValueG: G-component of the parameter

NewValueB: B-component of the parameter

NewValueA: A-component of the parameter

This function can be used for communication between scripts. When this function is called, the function onReceive is called in all scripts that have subscribed to the corresponding topic.

Topic: Topic

Argument: Data sent with the topic. Can be any Lua data type.

This function allows the script to subscribe to a topic. This will notify the script via the on Receive function when another script calls the publish function with this topic.

Topic: Topic

With this function, billboards can be shown or hidden.

Name: Name of the billboard

Visible: Determines whether the billboard should be visible.

With this function, individual assistance systems can be disabled or enabled.

System: Name of the assistance system to be disabled/enabled. Possible values: ABS, TCS, ESC, AutoHold, HillStartAssistant.

Disabled: Determines whether the system should be disabled or enabled. True deactivates the system, and false reactivates it.

This function allows the script to tell the engine whether the button for starting or stopping the engine is pressed.

Value: Determines whether the button is pressed.

This function can be used to set whether the automatic transmission should be in manual or automatic shifting mode, whereby only one of the two is always active when this function is used. If manual and automatic shifting is to be allowed at the same time, the setTransmissionManualShiftingAllowed and setTransmissionAutomaticShiftingAllowed functions should be used instead.

Enabled: True means that only manual shifting is allowed, and false means that only automatic shifting is allowed.

This function can be used to toggle the automatic transmission between manual and automatic shifting modes. When this function is used, only one of the two is active at a time. If manual and automatic shifting is to be allowed at the same time, the setTransmissionManualShiftingAllowed and setTransmissionAutomaticShiftingAllowed functions should be used instead.

This function can be used to set whether the automatic transmission allows the manual shifting of gears.

Allowed: Sets whether manual shifting is allowed.

This function can be used to set whether the automatic transmission shifts gears automatically.

Allowed: Sets whether automatic shifting is allowed.

This function can be used to select which shifting mode the transmission should use.

Mode: Index of the ShiftingMode to be used

This function can be used to request the gearbox to shift down a gear. Only works with manual transmission or if the manual shift mode is active.

Value: Indicates whether the gear change is requested.

This function can be used to request the transmission to shift up a gear. Only works with manual transmission or if manual shift mode is active.

Value: Indicates whether the gear change is requested.

This function can be used to request the transmission to downshift a drive mode (P-R-N-D). Only works for automatic transmission or electric cars.

Value: Indicates whether the change is requested.

This function can be used to request the transmission to shift up a drive mode (P-R-N-D). Only works with automatic transmission or electric cars.

Value: Indicates whether the change is requested.

This function can be used to request the transmission to shift down a drive mode (P-R-N-D) or gear.

Value: Indicates whether the change is requested.

This function can be used to request the transmission to shift up a drive mode (P-R-N-D) or a gear.

Value: Indicates whether the change is requested.

This function can be used to request the gearbox to activate the park mode.

Value: Indicates whether the park mode is requested.

This function can be used to limit the maximum torque of the engine.

Value: maximum torque in Nm. 0 means no limit.

With this function, the brightness of a light source can be set.

Name: Name of the light source

Intensity: Brightness

This function can be used to query whether the player camera is currently in the interior view or in an exterior view. The function returns a boolean that is true if the camera is in the interior view.

This function sets the visibility of an attachment.

Name: Name of the attachment

Visible: Whether the attachment should be visible

This function notifies the cross menu that the state of a vehicle function has changed.

Function: Name of the function

State: New state

This function sets the handbrake of the vehicle.

Value: Position of the handbrake: 0 = completely released, 1 = completely applied.

This function can be used to perform a LineTrace, e.g. for parking sensors. The function returns the distance from the starting point to the first collision.

BoneName: Name of the bone used as a reference for the coordinates.

StartOffset: Start position of the LineTrace relative to the position of the bone.

EndOffset: End position of the LineTrace relative to the position of the bone.

This function sets the brake to a certain minimum value.

Value: Minimum value to set the brake to (0 bis 1)

This function disables or enables a SceneCapture (used for mirrors or cameras). For example, this can be used to only enable the rearview camera, when reverse gear is engaged for better performance.

AttachmentName: Name of the attachment, where the SceneCapture is defined

Enable: Whether the SceneCapture should be enabled

Continued in the next section.

Continued from the previous section.

This function opens a playlist or a radio station.

Name: Name of the playlist or radio station

Sets the Music Player to Play.

Sets the Music Player to Pause.

Toggles play or pause.

Switch to the next song. Doesn't work, if a radio station is playing.

Switch to the previous song. Doesn't work, if a radio station is playing.

Switch to the next playlist. Ignores radio stations.

Switch to the previous playlist. Ignores radio stations.

Switch to the next radio station. Ignores playlists.

Switch to the previous radio station. Ignores playlists.

Switch to the next playlist or radio station.

Switch to the previous playlist or radio station.

Seek a certain position in the current song.

Value: Position to seek: 0 is at the beginning of the song, and 1 is at the end.

Sets the Music Player's loop function, so that it loops the current playlist.

Value: Whether the loop function should be enabled

Toggles the Music Player's loop function, so that it loops the current playlist.

Sets the Music Player's loop function, so that it loops the current song.

Value: Whether the loop function should be enabled

Toggles the Music Player's loop function, so that it loops the current song.

Sets the Music Player's shuffle function, so that it selects random songs from the current playlist.

Value: Whether the shuffle function should be enabled

Toggles the Music Player's shuffle function, so that it selects random songs from the current playlist.

Sets the Music Player's audio volume.

Value: Value (0 to 1) to set the volume to.

Increases the Music Player's audio volume by a certain amount.

Value: Value, by which the volume should be increased

Decreases the Music Player's audio volume by a certain amount.

Value: Value, by which the volume should be decreased

This function tells the Music Player, whether the player is currently outside of the vehicle so that the music sounds more muffled.

Value: Determines whether the effect should be active. This value should be true if the player is outside of the vehicle and all windows and doors are closed.

Continued in the next section with Datatypes.

VehicleTransmissionState Transmission: State of the gearbox

VehicleEngineState Engine: State of the engine

VehicleAssistanceSystemsState AssistanceSystems: State of the assistance systems

EnvironmentState Environment: State of the environment

VehiclePlayerInputs Inputs: Player inputs through input devices. Note: Inputs via the cross-menu or by interacting with vehicle attachments are not considered here.

Float DeltaSeconds: Time in seconds since the last tick

Float Speed: Vehicle speed in km/h

Float AverageSteerAngle: Average steering angle

Float SteeringWheelAngle: Steering angle

Vector Acceleration: Acceleration forces acting on the vehicle

Array<Rotator> WheelAnimationRotations

Array<Float> MotionBlurFactor

Array<Rotator> TireAnimationRotations

Array<Vector> WheelAnimationRotations

Array<Vector> WheelAnimationTranslations

Float ResourceLevel: Fill level of the tank or battery

Bool InTunnel: Is the vehicle in a tunnel?

Bool InUnderpass: Is the vehicle in an underpass?

Float DrivenMeters: Distance in metres that the vehicle has travelled in total.

Float DrivenMetersSinceStart: Distance in metres that the vehicle has travelled since the start of the game.

MusicPlayerTickData MusicPlayer: State of the music player.

Float Torque: Torque output of the gearbox

Int GearIndex: Currently engaged gear

Float ClutchPosition: Current position of the clutch

int DriveModeIndex: Index of the current drive mode

Array<Int> AllowedDriveModes: Currently allowed drive modes

Float CurrentGearRatio: Current gear ratio of the gearbox

Float ClutchSpeed: Clutch speed

Float ClutchTorque: Clutch torque

Bool ClutchIsSlipping: Is the clutch currently slipping?

Float ClutchEngineSpeedDifference: Difference between engine speed and clutch speed

Bool SwitchingGearFailed: This is true if engaging a gear failed, e.g. because the clutch was not sufficiently depressed or the speed difference is too great.

Bool AutomaticShiftingAllowed: Is the transmission currently allowed to shift gears automatically?

Bool ManualShiftingAllowed: Is the player currently allowed to manually shift gears in the automatic transmission?

Int SelectedShiftingMode: Index of the currently selected shifting mode.

Bool ManualUpshiftingInputReceived: This is true if the transmission has received a request to manually shift up a gear. Can be used, for example, to animate gearshift paddles.

Bool ManualDownshiftingInputReceived: This is true if the transmission has received the request to manually shift down a gear. Can be used, for example, to animate gearshift paddles.

Bool DriveModeUpInputReceived: This is true if the transmission has received the request to shift up a drive mode (P-R-N-D). Can be used, for example, to animate gearsticks.

Bool DriveModeDownInputReceived: This is true if the transmission has received the request to downshift a drive mode (P-R-N-D). Can be used, for example, to animate gearsticks.

Bool GearshiftInProgress: This is true if a gear shift is currently taking place in the automatic transmission.

Float RevolutionsPerMinute: Revolutions per minute of the engine.

Float CurrentPower: Current engine torque in Nm

Float EngineTemperature: Current cooling water temperature in °C

Bool RecuperationBrakeLight: Is the recuperation currently so strong that the brake light should be switched on?

Float FuelInjection: Current fuel injection (0 to 1)

Bool EngineStarter: Is the starter currently active?

Bool On: Is the engine currently running?

Float LimitTorque: Value to which the engine torque is currently limited. 0 means no limit.

Bool ABSDisabled: Is ABS currently disabled?

Bool ABSIntervention: Is ABS currently active?

Bool TCSDisabled: Is Traction Control currently disabled?

Bool TCSIntervention: Is Traction Control currently active?

Bool ESCDisabled: Is ESC currently disabled?

Bool ESCIntervention: Is ESC currently active?

Bool AutoHoldDisabled: Is Autohold currently disabled?

Bool AutoHoldActive: Is Autohold currently active?

Bool HillStartAssistantDisabled: Is the hill start assistant currently disabled?

Bool HillStartAssistantActive: Is the hill start assistant currently active?

DateTimeLuaState DateTimeLua: Time formatted for Lua (will probably also include the date later).

Float SunBrightness: Brightness of the sun

Hour: Hour

Minute: Minute

Second: Second

Float ThrottleInput: Throttle input (0 to 1)

Float BrakeInput: Brake input(0 to 1)

Float SteeringInput: Steering input (-1 to 1)

Float ClutchInput: Clutch input (0 to 1)

Bool DriveModeUpRequested: Next drive mode requested

Bool DriveModeDownRequested: Previous drive mode requested

Bool DriveModeParkRequested: Park mode requested

Bool DriveModeOrGearUpRequested: Next drive mode or gear requested

Bool DriveModeOrGearDownRequested: Previous drive mode or gear requested

Bool GearUpRequested: Next gear requested

Bool GearDownRequested: Previous gear requested

Int RequestedGearIndex: Requested gear index

Bool GearRequested: True, if the player has just requested a certain gear

Bool ToggleEngine: Engine start/stop button pressed

Bool AutoClutch: Automatic clutch enabled

VehicleMetaDefinition Meta: Vehicle Metadata

Map<VehicleAppearanceProperty, VehicleAppearanceDefinition> AppearanceDefinitions: Vehicle appearance definitions

Guid Id: Id (Guid = Global unique identifier)

String SkeletonReferencePath: Skeleton reference path

Map<String, VehicleCameraDefinition> Cameras: Camera definitions

VehiclePowerTrainDefinition PowerTrain: Power Train definition

Guid SelectedProfileId: Id of the selected profile

VehicleAssistanceSystemsDefinition AssistanceSystems: Assistance systems definition

Array<VehicleCrossMenuFunctionDefinition> CrossMenuFunctions: Cross-menu functions

String Manufacturer: Manufacturer

String Model: Model name

String Author: Author

String Version: Version

String Description: Short description of the vehicle

Bool PlayerDriveable: Can this vehicle be driven by the player?

String Category: Vehicle type. Possible values: Sedan, Coupe, SportsCar, StationWagon, Hatchback, Convertible, Suv, MiniVan, PickUp, Other

VehicleEngineDefinition Engine: Engine definition

VehicleTransmissionDefinition Transmission: Gearbox definition

VehicleDifferentialDefinition Differential: Differential definition

Continued in the next section.

Defines an engine. For a description see the section "Configure Power Train".

String Identifier

Float MaxPower

Float MaxRecuperationPower

Float MaxTorque

Float RecuperationEfficiency

Bool UseCustomTorqueCurves

Bool UseCustomRecuperationCurves

Float MinRecuperationTorqueForBrakeLight

Float MaxReversingSpeed

Float PowerOutputChangeRate

Float RevUpSpeed

Bool UseOnePedalDrivingThrottleResponse

Float OnePedalDrivingRecuperationMaxThrottlePositionAtSpeed

Float IdlePower

Float IdleRPM

Float IdleRPMAfterColdStart

Float StallRPM

Float StallTime

Float StarterTorque

Float StarterTime

Float CoolingFactor

String MaxTorqueCurve

String ThrottleResponseCurve

String ThrottleResponseAccelerationCurve

String ThrottleResponseRecuperationCurve

String MaxRecuperationCurve

String BrakeRecuperationCurve

String MinTorqueCurve

String StallingTorqueCurve

String EngineEfficiencyCurve

String ThrottleEfficiencyCurve

Defines a gearbox. For a description see the section "Configure Power Train".

String Identifier

VehicleTransmissionType TransmissionType

Float BaseRatio

Float ChangeTime

Float Efficiency

Float MaxClutchTorque

Float MaxClutchTorqueSlipping

Float ClutchFullyDisengagedAtBrakePosition

Float ClutchDisengagesAtSpeed

Float MaxClutchSpeed

Float MaxClutchSpeedGearSwitching

Float MaxClutchSpeedDifferenceForEngagingGear

Float DrivingOffClutchFactor

Float DrivingOffMaxClutchSpeed

Float DrivingOffMinClutchSpeed

Float DrivingOffMinRPM

Float DrivingOffMaxRPM

Float MinCreepingSpeedAtIdle

Float MaxCreepingSpeedAtIdle

Float MaxAllowedRpm

Float KickdownTreshold

Bool DynamicShiftPoints

VehicleGearDefinition ReverseGear

Array<VehicleGearDefinition> ForwardGears

String DynamicShiftingThrottleResponseCurve

String ClutchCurve

Bool AutomaticallyShiftToParkWhenEngineIsOff

Bool AutomaticallyShiftToFirstGearAtStandstill

Bool UseClassicGearSelectorPattern

String Type: Type. Possible values: AllWheelDrive, FrontWheelDrive, RearWheelDrive

Float FrontRearSplit: Drive force distribution front/rear with all-wheel drive

Defines assistance systems. For a description see Configure assistance systems.

VehicleABSDefinition ABS

VehicleTCSDefinition TCS

VehicleESCDefinition ESC

VehicleAutoHoldDefinition AutoHold

VehicleHillStartAssistantDefinition HillStartDefinition

Defines a cross-menu function. For a description see Cross Menu.

String Category

String Name

Array<String> States

Int DefaultState

String Icon

VehicleProfileMeta Meta: Vehicle profile metadata

Map<VehicleAppearanceProperty, VehicleAppearancePropertyValues> Appearence: Appearance

VehicleResourcesDefinition Resources: Resources definitions

VehicleSteeringDefinition Steering: Steering definition

VehicleChassisDefinition Chassis: Chassis definition

Array<VehicleWheelDefinition> Wheels: Wheel Definition

Array<VehicleAttachmentDefinition> Attachments: Attachment definitions

Map<String, VehicleLightDefinition> Lights: Lightsource definition

Map<String, VehiclePostProcessingVolumeDefinition> PostProcessingVolumes: PostProcessingVolume definitions

Array<VehicleLightBillboardDefinition> Billboards: Billboard definitions

String Name

Guid Id

Guid VehicleId

Bool bIsDefault

Bool bIsValid

String Path

DateTime LastModificationDate

Float MaxEngineResourceLevel

Float InputRatio

String MeshReferencePath

Float Width

Float Length

Float Height

Float Mass

Float DragCoefficient

Float DownforceCoefficient

Vector CenterOfMassOffset

String MeshReferencePath

String MeshReferencePathForMotionBlur

Bool StationaryMeshAlwaysVisible

Bool StationaryMeshCustomDepth

Bool MotionBlurMeshStatic

Float MotionBlurTreshold

Float MotionBlurRange

Float MotionBlurScale

String VerticalPosition

String HorizontalPosition

Vector Offset

Bool AffectedByEngine

Bool AffectedByBrake

Bool AffectedBySteering

Bool AffectedByHandBrake

Float RimRadius

Float Radius

Float Width

Float FrictionForceMultiplier

Float CorneringStiffness

Float SideSlipModifier

Float SlipThreshold

Float SkidThreshold

Float SpringRate

Float SpringPreload

Vector SuspensionAxis

Vector SuspensionForceOffset

Float SuspensionMaxRaise

Float SuspensionMaxDrop

Float SuspensionDampingRatio

Float SuspensionSmoothing

Float WheelLoadRatio

Float RollbarScaling

Float MaxSteerAngle

Float MaxBrakeTorque

Float MaxHandBrakeTorque

Float MaxBrakeSpeed

String Name

String MeshReferencePath

Array<VehicleAttachmentMaterialOverrideDefinition> MaterialOverrides

String Target

String Role

Vector PositionOffset

Rotator RotationOffset

Bool TriggerClickEvent

Map<String, Int> DynamicMaterialIndices

Map<String, String> DynamicMaterialSlotNames

Array<VehicleDynamicDisplayDefinition> DynamicDisplays

VehicleInteractionDefinition Interaction

VehicleAttachmentSceneCaptureDefinition

Map<String, Int> CustomDataInts

String SlotName

Int SlotIndex

String MaterialReferencePath

String Name

Vector Offset

Vector Scale

Rotator RotationOffset

Vector2D Resolution

Bool ContainsNavigation

Vector2D NavigationResolution

Bool Interactable

String Identifier

Vector InfoOffset

Rotator InfoRotationOffset

String InfoText

String SecondaryInfoText

Bool AllowLongInteraction

Bool SupportSecondaryInteraction

Bool Enabled

String TargetTextureReferencePath

Vector PositionOffset

Rotator RotationOffset

Float ProjectionFov

String Type

Vector Position

Rotator Rotation

Float Intensity

Float AttenuationRadius

Bool CastsShadows

Bool AffectsWorld

LinearColor Color

Float InnerConeAngle

Float OuterConeAngle

Vector Position

String Identifier: Engine identifier

VehicleEngineType Type: Engine type. Possible values: Combustion, Electric, Other

Map<String, LuaValue> Parameters: Engine parameters

String Identifier

VehicleTransmissionType Type

Array<VehicleGearDescription> Gears

Array<VehicleEngineDriveModeDescription> DriveModes

Map<String, LuaValue> Parameters

Bool IsPlaying: Whether the music player is currently playing

Bool IsLooping: Whether the loop function is currently active

Bool IsLoopingOneSong: Whether the loop function for one song is currently active

Bool IsShuffled: Whether the shuffle function is currently active

Array<String> AvailablePlaylists: Contains all available playlists

Array<String> AvailableRadioStations: Contains all available radio stations

Array<String> AvailablePlaylistsAndRadioStations: Contains all available playlists and radio stations

String PlaylistName: The name of the current playlist or radio station

String Artist: The artist of the current song. This value is empty while playing a radio station.

String Title: The title of the current song. This value is empty while playing a radio station.

Float TrackLength: The length in seconds of the current song. This value is empty while playing a radio station.

Float TrackTime: The playback time of the current song. This value is empty while playing a radio station.

Float TrackProgress: The progress of the current song (0 to 1). This value is empty while playing a radio station.

Float Volume: The currently set volume (0 to 1)

Bool IsRadioStation: Whether the music player is currently playing a radio station (true) or a playlist (false).

For vehicle sounds, the use of Unreal Engine's MetaSounds is recommended. Sounds to be used must be imported in the Unreal Editor and should have a sampling rate of 44100 Hz. Any number of MetaSound assets can be created, which are controlled via Lua scripts.

To integrate a MetaSound asset into a vehicle, the reference to the object must first be copied. This is obtained by right-clicking on the MetaSound asset and selecting "Copy Reference". Then requireMetaSound can be called in the Lua script. This links the MetaSound asset with the respective Lua script and it can be controlled.

This function links a MetaSound asset to the current script. Only one asset can be linked to a script at a time.

Path: Reference to the MetaSound asset.

This function links a MetaSound asset to the current script and places it at a specific position in the vehicle. Only one asset can be linked to a script at a time.

Path: Reference to the MetaSound asset.

X: X-Coordinate of the sound position

Y: Y-Coordinate of the sound position

Z: Z-Coordinate of the sound position

Sets a float parameter in the linked MetaSound asset.

Name: Name of the parameter

Value: value to which the parameter should be set

Sets an integer parameter in the linked MetaSound asset.

Name: Name of the parameter

Value: Value to which the parameter should be set

Sets a Boolean parameter in the linked MetaSound asset.

Name: Name of the parameter

Value: Value to which the parameter should be set

Calls a trigger in the linked MetaSound asset.

Name: Name of the trigger

To create a display, there is the attachment parameter "dynamicDisplays". This is an array which contains display definitions. A display definition has the following parameters:


To draw textures on displays, the textures must first be imported in the Unreal Editor. Then a brush must be created for each texture and the respective texture must be assigned as an "image" in the brush.


To draw monochrome areas, it is also possible to omit the image in the brush and set the desired colour as "tint".

In order to use certain fonts, they must first be imported into the Unreal Editor. Unreal creates a FontFace-Asset as well as a Font-Asset for each font. The font asset must be registered later in the script. To do this, a reference to the asset is required, which can be obtained by right-clicking on the asset and selecting "Copy Reference".

The actual drawing of the display is done in the script. First, the correct context must be selected using activateDynamicDisplayContext. Then all brushes and fonts to be used have to be registered with registerBrush and registerFont. Afterwards, appropriate display elements can be created with createRectangle and createText. These elements can then be dynamically updated later to react to changing vehicle conditions.

This function sets the context to the specified display. All other functions always act on the active display, which is why this function must always be called first.

DynamicDisplayName: Name of the display to which the context is to be set.

This function removes all existing elements from the active display.

This function registers a brush for the active display. Please note that a registration is only valid for the active display and a brush that is to be used on several displays must also be registered for all displays. This function returns a BrushHandle, which can be used in other functions to reference this brush.

Path: Reference path to the brush asset.

This function registers a font for the active display. Please note that a registration is only valid for the active display and a font that is to be used on several displays must also be registered for all displays. As a return value, this function returns a FontHandle, which can be specified in other functions to reference this font.

Path: Reference path to the font asset.

Creates a rectangle at the specified position with the specified size using the specified brush. As a return value, this function returns a RectangleHandle, which can be used in other functions to reference this rectangle.

PositionX: X-coordinate of the position in pixels where the rectangle is to be drawn.

PositionY: Y-coordinate of the position in pixels where the rectangle is to be drawn.

SizeX: Width of the rectangle in pixels.

SizeY: Height of the rectangle in pixels.

BrushHandle: Handle of the brush to be used.

Creates a text with the given parameters. As a return value, this function returns a TextHandle, which can be specified in other functions to reference this text.

Text: Text

PositionX: X-coordinate of the position in pixels where the text is to be drawn.

PositionY: Y-coordinate of the position in pixels where the text is to be drawn.

SizeX: Width of the text in pixels.

SizeY: Height of the text in pixels.

FontHandle: Handle of the font to be used.

FontSize: Font size

ColorR: R-component of the font colour to be used

ColorG: G-component of the font colour to be used

ColorB: B-component of the font colour to be used

Creates a rectangle containing a minimap with the current navigation. Only works if the DynamicDisplay parameter containsNavigation is set to true in the attachment. As a return value, this function returns a RectangleHandle, which can be used in other functions to reference this rectangle.

PositionX: X-coordinate of the position in pixels where the rectangle is to be drawn.

PositionY: Y-coordinate of the position in pixels where the rectangle is to be drawn.

SizeX: Width of the rectangle in pixels.

SizeY: Height of the rectangle in pixels.

With this function, the zoom level of the minimap can be set.

Zoom: New zoom value

With this function, the line thickness of the navigation on the minimap can be set.

LineThickness: New line thickness

With this function, the size of the PointOfInterest markers on the minimap can be set.

Size: New size

Continued in the next section.

Continued from the previous section.

With this function, the text of an existing TextHandle can be updated.

TextHandle: TextHandle whose text is to be changed.

NewText: New text

With this function, the font size of an existing TextHandle can be updated.

TextHandle: TextHandle whose font size is to be changed.

NewFontSize: New font size

This function can be used to update the text colour of an existing TextHandle.

TextHandle: TextHandle whose font size is to be changed.

NewColorR: R-component of the new text colour.

NewColorG: G-component of the new text colour.

NewColorB: B-component of the new text colour.

NewColorA: A-component of the new text colour.

This function can be used to update the font of an existing TextHandle.

TextHandle: TextHandle whose font is to be changed.

NewFontHandle: FontHandle of the new font.

This function can be used to centre text.

TextHandle: TextHandle whose text is to be centred.

AlignInCenter: True to centre the text, false to no longer centre it.

With this function, text can be set right-aligned.

TextHandle: TextHandle whose text is to be right-aligned.

AlignRight: True to set the text right-aligned, false to set it left-aligned

With this function, the size of an existing rectangle can be changed.

RectangleHandle: RectangleHandle of the rectangle to be resized.

SizeX: New width in pixels

SizeY: New height in pixels

This function can be used to change the position of an existing rectangle.

RectangleHandle: RectangleHandle of the rectangle that is to be changed.

PosX: New X-coordinate in pixels

PosY: New Y-coordinate in pixels

This function can be used to rotate an existing rectangle.

RectangleHandle: RectangleHandle of the rectangle that is to be changed.

Angle: New rotation angle

RotateAroundPointX: X-coordinate of the point around which the rectangle is to be rotated.

RotateAroundPointY: Y-coordinate of the point around which the rectangle is to be rotated.

This function hides an element.

Handle: Element handle.

This function shows an element.

Handle: Element handle

With this function, the brush used for a rectangle can be changed.

RectangleHandle: RectangleHandle to the rectangle whose brush is to be changed

BrushHandle: BrushHandle for the brush to be used.

This function determines whether the active display should be rendered.

Active: Should the display be rendered?

In order for a vehicle to function correctly with the cross menu, some adjustments are required.

In the vehicle's "data.json" it must be defined which functions the vehicle should provide in the cross menu. For this purpose, any number of cross menu functions can be created under "CrossMenuFunctions", which have the following parameters:



This function can be created in the script and is called by the control pad whenever the player clicks on a function in the control pad. The vehicle script should then ensure that the function selected by the player is actually executed (e.g. the light switch is turned to the corresponding position and the light is switched on).

Function: Name of the called function (e.g. "lightswitch"). Corresponds to "name" in "CrossMenuFunctions" in the "data.json".

State: New state to which the function is to be set (e.g. "lowbeam"). Corresponds to the corresponding entry in "states" in "CrossMenuFunctions" in the "data.json".

This function informs the cross menu that the state of a vehicle function has changed. This function should always be called by the script when the state of a function in the direction pad has changed, regardless of whether the change was triggered by onCrossMenuChanged or in some other way.

Function: Name of the function. Must correspond to a function name specified in "CrossMenuFunctions" in the "data.json".

State: New state. Must correspond to a function state specified in "CrossMenuFunctions" in "data.json".

Interaction is when the player targets a vehicle attachment and then presses an interaction button. There are primary and secondary interactions and a distinction is made between pressing and releasing.

There are two different types of interaction. This distinction is necessary because a long press of the interaction button normally causes the player to enter or exit the vehicle. In this case, it is not possible to distinguish between the beginning and the end of the interaction because it is only when the button is released that it is determined whether the interaction is triggered at all. Therefore, as a second type, there are so-called "long" interactions that suppress the entry/exit and are triggered both at the beginning and at the end of the keystroke. This makes it possible, for example, to implement long keystrokes in the cockpit.

Interactions are configured for one attachment at a time. For this purpose, there is the attachment parameter "interaction", which has the following parameters:


This function in the script is always called when an attachment is interacted with.

InteractionName: Name of the interaction, corresponds to the parameter "identifier". If "identifier" is not defined, the role of the attachment is used instead.

Secondary: Is true if it is the secondary interaction.

Pressed: Is true if the interaction key was pressed and false if the interaction key was released. If the attachment does not support long interactions, this variable is always false.

It is also possible to set up display interactions. These are triggered whenever the player clicks on a display. For display interactions to work, the corresponding DynamicDisplay must have the supportsInteraction parameter set to true.

This function in the script is always called when a display is interacted with.

DisplayName: Name of the display being interacted with.

AttachmentName: Name of the attachment to which the display is assigned. This distinction is important if there are displays in several attachments that have the same name.

Pressed: Is true if the interaction key was pressed and false if the interaction key was released.

CoordinateX: X-coordinate of the position in pixels where the display was clicked.

CoordinateY: Y-coordinate of the position in pixels where the display was clicked.

By now you've probably tested your mod frequently in CityDriver to make sure everything works as intended. In case you want to share your mod with the community, you can upload your mod in the "Vehicle Selection" in CityDriver to the Steam Workshop - your mod will be hidden by default, so you can test your mod with your friends before you publish it to the entire community.

You can find the option "Workshop Settings" in the bottom right corner of the UI, shortcut R.

Submitting your mod will take a while as the files are being uploaded to Steam Workshop in the background.

When your mod files have been successfully submitted to the Workshop you can find your mod in your Steam Profile under "Workshop Submission".

You can also update and publish your mod later via the "Workshop Settings" in the "Vehicle Selection" of CityDriver too.

Make sure to check your mod on the Steam Workshop before you publish it, as you may have to check Steam's Workshop Agreement occasionally. Also, uploading a preview image for your mod can currently only be done via the Steam Workshop itself and CityDriver provides a convenient Photo mode for screenshots.

In case you've deleted your mod on the Steam Workshop and want to upload it via CityDriver again for whatever reason, you will have to delete the number of the workshopId in the default.json of your mod files, e.g.

Before:
After:



And that's about it for this version of CityDriver's vehicle modding. Feel free to write your comments down below or join us on our Discord: https://discord.gg/viewapp-community