Put your mod zip file...the whole zip...into the vehicles folder. Unzip it from there into the same vehicles folder. When done you should see the zip file below and the vehicle folder above within the vehicles folder. I don't think anything has changed with this in 0.3.7.8.
it seems its only the d15 and gm it works on the covet also anyone notice? - - - Updated - - - cars that i have reflection and the ones that dont all used the exact same red working not working not working working i thought this was fixed? working working broken textures not working working sorry about all the images