I am attempting to modify the custom joints vehicle implementation so the wheels rotate around the X axis and the car points in the positive Z direction. So far I did a search and replace switching m_x / m_z and m_front / m_right. Right now it crashes due to a bad matrix being created somewhere.
If anyone knows this well enough I am interested in hiring someone to fix this. Please contact me if you are interested in making some money. I will make your resulting code open-source and post it here for anyone to use.