This is a generic car like robot. It is driven using steering, power and braking as provided by the steer/force actuator. This vehicle uses the Blender vehicle wrapper constraint, to give it a realistic behaviour, including the interaction of the wheels with the ground and suspension.
Use the Properties >> Physics panel in Blender to adjust the Mass of the robot.
The friction coefficient of the robot can be adjusted in its .blend file. When the robot is selected, the Logic Editor panel will display its Game Properties.
Also affects steering wheel’s ability to turn the vehicle. A value of 0 gives very low acceleration. Higher values permit a higher acceleration.