Ok, I lied. I don't know why I said the transistors were wired like that, they have 9v going to collector, then emitter through the motor then to ground. The reason I am using these transistors is because I had purchased a pack of 100 from a hobby pack so I have a lot laying around, and also as a learning process in starting with the basics and building circuits from scratch.
Either way, what I've noticed is if I send the 9v through the base of the transistor, it allows all of the collector voltage through (full power to motors), but with just the small signal from the arduino outputs, not much goes through.
And yes, the car uses 6 1.5v nimh batteries
Here's a quick sketch of the motor portion of the schematic:
schematic (1.6 MB)