There are more than a few scripts and rigging tools available for rigging automobiles in Maya. Some offer an easy way to get wheels rotating based on the movement of the car, others will add in steering, and even others will incorporate a suspension system.
The easyCarDriver Mel script is a tool to automatically create a 4-wheeled car rig in Maya.
A new offering however, seems to roll all of those features into one car rigging script. The EasyCarDriver script for Maya, is a tool that will automatically create a 4-wheeled car rig in Maya.
You can easily animate the motion for the vehicle by using a curve in the scene. The script will also make the wheels stick to the ground, even if the ground is a terrain.
EasyCarDriver give you a fast set up, dynamic suspension, automatic wheel ground contact, automatic wheel rotation and offset attributes for adjusting/animating you car on top off the generated animation.