just for you and for everybody who can't read... from lfs.net(FAQ):
"Answer to: Can I make my own cars/tracks for LFS?: No - Live for Speed is still in development therefore there are no car or track editors available at this time. Also it's not yet possible to import other 3d formats into the game. However we will probably release the editors at some point in the future when most of the LFS development is finished. "
and yes you can put a car in to the game(there is a thread in the screenshot section), but i don't know how, and i don't care it...