New vehicle support can be added by creating a pinkslip item See here: https://github.com/xyberviri/CarWanna/blob/main/Tools/ConfigGenerator/EXAMPLEOUT_pinkslips.txt

Then by creating a recipe to call the item, See here:
https://github.com/xyberviri/CarWanna/blob/main/Tools/ConfigGenerator/EXAMPLEOUT_recipes.txt

If you need to create these configs in bulk you can try using the power shell script i use to create the addons on my github here:
https://github.com/xyberviri/CarWanna/tree/main/Tools/ConfigGenerator

Take a look at the input and output files, most of the time i dont change anything on this except the file prefix that is generated.

note the "GasTank = 100," and "HasKey = true," values i manually remove after verifying if a vehicle has a key or gas tank (ie trailers)

Fuel trailers use the value of "FuelTank = 100," and to control how much fuel a trailer has, the actual part is store in an array named "CW_fueltankPartNames", it is pre populated with the fuel tanks for Ki5 Vehicles "1000FuelTank", "500FuelTank".