Are you changing the core game components.xml file or are you making a mod? If you're altering the core game files, you have a chance to lose your work anytime the game is updated or Steam does a file verification. It is suggested to make a mod file.

Beyond that, did you include the .mesh file in one of the artwork zip files? For the core game, cars are located in the cars.zip file. For a mod, the .mesh can be in any of the linked .zip files you include with the mod.

I changed the core components.xml, but just in case I saved a copy on the desktop. I'm plased mesh in cars.zip, but it did not help.

Are you checking RnD in game or are you checking with the car designer in the main menu?

I'm checking with the car designer in the main menu

Post the line of xml for your car design here.

<car name="AlfaRomeo12C" type="13201" model="Alfa_Romeo_12C.mesh" year="1965" death="1986" designreq="0" pass="1" localName="0" localDesc="0" localParam="0"/>

You're using a localized type name, but disabled localization with the last three flags. Set localDesc to 1.

Now the body has appeared, but when it is selected, the game crashes with the following log:

21:45:29: OGRE EXCEPTION(5:ItemIdentityException): Entity is not animated in Entity::getAnimationState at ..\..\ogre\OgreMain\src\OgreEntity.cpp (line 667)

And I do not understand: why? I animated the mesh. I can send it (mesh made in Blender)

I have no way of checking blend files. I can look at the .mesh for you when I get into the office in about 6 hours.

Most likely you did not export your animations properly. See MediaevalRocket's tutorial for bforartist and the various keyframe/exporting requirements: http://wiki.gearcity.info/doku.php?id=artwork:models_vehicles:bforartist

The trouble is that I did everything according to this instruction.

UPD. I forgot to mention that I converted this mesh from a XML file using OgreXMLConverter. Blender2Ogre converted only until the creation of the XML file and the .material files, and then show the WinError2 error. And, judging by the mesh loading log, the materials did not load on it, although they exist.

Looking at the .mesh's xml file, your pose animations do not target a specific submesh, and your animation names are not named correctly. You have for example "Key 1", "Key 2" , etc. The game expects at the least, "Entire Body_Complete_Length", "Entire Body_Complete_Width", and "Entire Body_Complete_Height" animation names.

I assume your issues are around http://wiki.gearcity.info/doku.php?id=artwork:models_vehicles:bforartist#shape_keying down.

You may want to get in contact with MediaevalRocket, as my knowledge of blender is limited. Seems like he had similar problems, and it boiled down to not using the key shaping commands correctly: https://steamhost.cn/steamcommunity_com/app/285110/discussions/14/3596571824757485448/

I tried to rename, now this error:

16:58:38: OGRE EXCEPTION(5:ItemIdentityException): No state found for animation named 'Entire Body_Complete_Length' in AnimationStateSet::getAnimationState at ..\..\ogre\OgreMain\src\OgreAnimationState.cpp (line 330)

This, maybe, is connected with Key001.Action and other similar Actions, but I don\t know how to rename them.

UPD. No, not connected. Could rename, but got exactly the same error.

Convert your mesh to xml and see if the pose animations are taking the name. It sounds like it is not.

Solved the problem, and the model is shown, but model is somehow too small, microscopic.

Blender should have a unit scaling system of somesort. Try increasing that. I believe for maya/max we use 1 unit = 1 meter. But I am not sure. Mrx_ua is the guy to ask for that.