I'm assuming by tutorial you mean this?
http://vdrift.net/faqman/index.php?op=view&t=14
To answer your questions:
QNev Wrote:1. Before exporting, what axis do the different parts of the car have to face?
Positive Z is up, positive Y should point in the same direction that the nose of the car is pointing. Set your car up like this and then export the glass as one object called glass.joe, the body as one object body.joe, the interior as one object interior.joe. wheel.joe is just one single wheel. I believe it is a left wheel. The differences between the models are, glass can have [semi-]transparent textures, body gets a reflection, interior has none.
QNev Wrote:2. Where do the textures have to be or do they have to be bundled?
The textures go in data/cars/Car/size/ where Car is the name of the car and size is large, medium or small. large textures should be 512x512, medium 256x256, small 128x128. Each of the models you set up should have a corresponding texture in all 3 sizes. The textures are not bundled.