[KenWittlief]

logically, back emf is there when the motor is running. It is what limits the current at the motors top speed (otherwise the motor would always draw its stall current).

So.... if you power the motor up to full speed, it cannot generate more back emf than its already seeing when its running

therefore, unless you tow the robot behind your car, so that its wheels are spinning faster than it would when self powered (way faster), there should not be a problem.