Probably best to post in the game engine forum, if you want to control/drive the car in the game engine.
To control/drive the car, and to get the car to move on the road correctly in the game engine, that will have to be setup with the logic editor and probably some python scripts.
The basic movement is easy todo, realistic is harder, implementing hills can be done different ways, resposition wheel Z each frame, follow face interpolation, simulate physics.
Heres a basic example of movement, press P in the 3D view to play: http://www.pasteall.org/blend/30234
Though you may want to implement more realistic things, slowing down, gears, max speed, drifting, etcetera.
If the car mesh is parented to an armature, just add the logic to the armature object.
People on the game engine forum will probably be able to help more.