First things first here are the stats of all the vehicles I have found in game and the Offroad Car by testing.

Version history
1.0 - Tests done on 7/2/24 on game version 1.0.4
1.1 - Added "Gas per inventory" on 7/4/2024
1.2

• Added "Storage Unit" section on 7/5/2024
  
• Added all boats
  
• Switched "Last Thoughts" into " Vehicle Classes"
  
• Changed my overall description of the Offroad Car's use to be more in line with end game

• Location: Archipelago
  
• Price: 120 000
  
• Gas Mileage : 1.5L/100km
  
• Tank : 3.5L
  
• Inventory: 2
  
• Gas per inventory : 0.75L/100km

• Location: Archipelago
  
• Price: 200 000
  
• Gas Mileage : 3.5L/100km
  
• Tank : 40L
  
• Inventory: 6
  
• Gas per inventory : 0.58L/100km

• Location: Paraiso Peninsula
  
• Price: 300 000
  
• Gas Mileage : 4.5L/100km
  
• Tank : 60L
  
• Inventory: 10
  
• Gas per inventory : 0.45L/100km

• Location: Jungle
  
• Price: 400 000
  
• Gas Mileage : 7L/100km
  
• Tank : 70L
  
• Inventory: 16
  
• Gas per inventory : 0.4375L/100km

Now the Offroad Car doesn't offer it's stats before you can buy it, unlike cars from dealerships, so the way I calculated the gas mileage for it was by comparing it to the Moped. I used the 200 units of distance between the police station and the gas seller by the docks at Dueno Del Mar.




Stats from the experiment

Moped at the start :1.0L/3.5L
Moped at the end: 0.7/3.5L
Result: Loss of 0.3L or 1/5 of the 1.5L/100km mileage

Offroad at the start: 15.3L/70L
Offroad at the end: 13.9L/70L
Result: Loss of 1.4L or 1/5 of the (6.99) 7L/100km mileage

Knowing this, the best course of action to move around the map is to use the moped with military clothes and a big backpack for your daily use and one big can of gas should allow one full map rotation, 2 in the inventory slots should make sure that you will never not have gas.

• Location: Small Island
  
• Price: Free
  
• Gas Mileage : 1.2L/100km
  
• Tank : 6L
  
• Inventory: 5
  
• Gas per inventory : 0.24L/100km
  
• Speed : 47km/h

• Location: Archipelago
  
• Price: 129 000
  
• Gas Mileage : 1.2L/100km
  
• Tank : 6L
  
• Inventory: 5
  
• Gas per inventory : 0.24L/100km
  
• Speed : 47km/h

• Location: Archipelago
  
• Price: 165 000
  
• Gas Mileage : 1.3L/100km
  
• Tank : 8L
  
• Inventory: 7
  
• Gas per inventory : 0.185L/100km
  
• Speed : 68km/h

• Location: Callejon
  
• Price: 175 000
  
• Gas Mileage : 1.3L/100km
  
• Tank : 8L
  
• Inventory: 7
  
• Gas per inventory : 0.185L/100km
  
• Speed : 68km/h

• Location: Slav Bay
  
• Price: 315 000
  
• Gas Mileage : 2.4L/100km
  
• Tank : 270L
  
• Inventory: 5
  
• Gas per inventory : 0.48 L/100km
  
• Speed : 68km/h

• Location: Callejon
  
• Price: 315 000
  
• Gas Mileage : 1.6L/100km
  
• Tank : 270L
  
• Inventory: 9
  
• Gas per inventory : 0.177L/100km
  
• Speed : 79km/h

• Location: Slav Bay
  
• Price: 470 000
  
• Gas Mileage : 4.4L/100km
  
• Tank : 270L
  
• Inventory: 5
  
• Gas per inventory : 0.88L/100km
  
• Speed : 46km/h

• Location: Dueno del Mar
  
• Price: 750 000
  
• Gas Mileage : 2.7L/100km
  
• Tank : 270L
  
• Inventory: 5
  
• Gas per inventory : 0.54L/100km
  
• Speed : 97km/h

• Location: Dueno del Mar
  
• Price: 4 200 000
  
• Gas Mileage : 2.7L/100km
  
• Tank : 270L
  
• Inventory: 5
  
• Gas per inventory : 0.54L/100km
  
• Speed : 50km/h

• Location: Bahia de Oro
  
• Price: 6 9000 000
  
• Gas Mileage : 30L/100km
  
• Tank : 700L
  
• Inventory: 20
  
• Gas per inventory : 0.66L/100km
  
• Speed : 50km/h

• Location: Dueno Del Mar
  
• Price: 12 500 000
  
• Gas Mileage : 100L/100km
  
• Tank : 2000L
  
• Inventory: 30
  
• Gas per inventory : 0.3L/100km
  
• Speed : 50km/h

• Location: Bahia de Oro
  
• Price: 25 000 000
  
• Gas Mileage : 200L/100km
  
• Tank : 3000L
  
• Inventory: 45
  
• Gas per inventory : 0.225L/100km
  
• Speed : 50km/h

If you look at boats, the same can be said for the smallest boat.

You can easily do the water route that connects Callejon, the Jungle, Slav Bay and the coke lab/Dueno Del Mar for peanuts in gas with the starting motorboat and since it's small enough, it drives fast and well in that river and you can even get in between the small islands of Slav Bay.

White Squares with red X are docks, red line is the sea route that connects Callejon, Jungle, Slav Bay and Dueno Del Mar

The cars, just like boats, can be used as storage units outside of the hideouts that you can buy. In the event of a raid, your supplies, your products and some chemicals can be taken by the police, in order to make sure that you do not lose your products, it is recommanded to remove them from your hideouts and to stash them somewhere when you do not need them. That's where vehicles comes in.

Each vehicle has a number of hidden inventory spots that can be used to stash your products. Using the land vehicles and later on the yachts with high fuel cost, but also high secret inventory space, you can use them as movable unraidable (as far as I understand, will update if new information is brought up) storage units. Of course the high cost of fuel makes them less interesting to move them often, so I would try to find a location that is easily accessible and close enough of where you either produce the product and need to stash it or where you distribute the product and desire to stash it nearby.

I believe that the Offroad Car is the "yacht" of the cars, meant to be stationnary next to a lab or a ressource that you need to gather and move a lot of (for example, I use my offroad car as a gas holder by my coke lab after filling it in the docks at Dueno Del Mar, because I do not desire to walk a million miles with gas on me and I don't have a boat parked there for that reason yet).

There are 3 classes of vehicle in the game and that includes boats.

The fuel efficient vehicles.

Those are the Moped, the Yellow Car , the Motorboats (yes there's 2) and the Rib Motorboat. Those are your fuel efficient ways to move around the map. They offer enough speed and agility, with the drawback of not having big fuel tanks for long distance, but to do all the minute tasks and for short distances they require little refueling. Those are your "moving around the map quickly and a lot" choices.

The middle range vehicles.

Those are your Blue Car, Deluxe Rib Motorboat, Luxury Motorboat, Caballo del Mar and La Frente. Those have medium range storage space, fuel cost that is starting to be a bit high for a lot of use, although their tanks are substantial and allow for less refuelling on short distances, and they offer a lot more inventory space than the fuel efficient vehicles. Those are great to move a lot of product a short distance. For example, moving a lot of coca leaves between the coca leaves vendor and the Jungle's northern dock. The middle range vehicles are also great for moving a lot of produce between hideouts when you are emptying out a lab completely while expanding.

The storage units.

Those are your Offroad Car, Bong Voyage and La Ballena. They offer massive amount of storage and fuel tanks for abysmal fuel efficiency. Moving those vehicles will vary between expensive and basically using all the availalble gas in stock on the map just to keep it going 5 minutes. Those vehicles are more suited as storage units that you can move in order to suit your needs. They offer secret storage, which allows you to keep your products in secure locations and avoid the chance of losing your stocks to raids. Don't use those vehicles as your main vehicles to move around the map.

I know people are going to say "I'm making millions, why should I care about my mileage?". Sure that's true, it doesn't matter at the end of the game, use whatever you have for whatever purpose, but when you just getting to mid game and you see the 400k Offroad Car, know that it's a late game vehicle and you shouldn't use your limitted funds for it. If you truly need a vehicle with a large inventory, the Blue Car will give you a better bang for your buck otherwise the Mopped will give you the best gas per distance in the game and with clothes and large bags, you should be able to move all the products and items that you require at any given time with just that one little light boi. Remember there's classes of vehicles and use choose your method of transportation in order to fit those needs.