i would go with either the spray can or air brush. by all means listen to skklown, stay away from the brushes, the only thing they are good for are for cleaning out the car after racing!!
I have tried brush painting the car, it does no happen. if you want to see some pics it, just ask. (too painful to look *shivers*) put i will show them to you if you want.
btw Welcome to the forums Triz. We are very happy to have you here.
-shiporu