This site provides lots of good info about how to perform dynamics calculations on robots.  The site is for robots, but the math and physics here could apply to other things like RC cars.  There’s lots of good information about how to calculate what kind of motor torque you need, what kind of accelerations and velocities to aim for.

The section about the robot factor is basically about DC motor selection.  All it does is do a power balance between the energy provided by the motor and the energy required to move the vehicle at a particular speed an acceleration.

http://www.societyofrobots.com/mechanics_dynamics.shtml