Says Hack A Day,
"Brake and gas pedals are actuated using a wrench connected to a motor bolted to the floorboards of the car. The steering wheel has been replaced with a gear and connected to a motor using a motorcycle chain... An iPhone app has been written to wirelessly control the car of doom.
...They've also implemented the most unorthodox automotive interface yet, Power Wheels. A chain has been added to measure the orientation of the toy steering wheel, and an optical encoder is used to measure the speed of the tiny electric vehicle. It looks like it doesn't do the best job of translating to a full size vehicle, but it maxes out their style points."
Check out the videos below to see it in action, and learn how they did it.