In the 3D rendering, wheels (primitive 12) rotate just like when you swap the 6 vertices order in the car parameters. If it indeed comes from the vertices order, it has been once wrongly descripted on the stunts wiki. A front back / left right inversion breaks it.
QuoteThe first three vertices in a wheel primitive mark the center and the boundary points along the y and z axes of the circle facing the inside of the car. The last three vertices do the same, in the same order, for the circle facing the outside.
Wheel transformations are performed on fixed vertex positions. Since the first eight vertices of car[0-2] shapes are occupied by the bound box, vertices 9-14 and 15-20 are front wheels. Misplaced wheel vertices will lead to corrupted shape rendering.

