Hello there,
I am currently working on Robogator, the cocodrile like robot that can be built using LEGO Mindstorms 8547 Set, but definitively as soon as I am done with it I will build this small little car myself.
There are two versions of the same car: one with one NXT Brick and the other with two NXT Bricks where one is used as a (very expensive) remote control. Check this video of the car.
You can find the building instructions at: http://www.nxtprograms.com/NXT2/race_car/