How can you make a homemade toy car go the fastest?

I have to build a toy car myself without using any type of engine. It will being going down a ramp and it has to be completely self propelled by gravity. Any ideas on how to make the car? And how to make it the fastest possible?|||Well, scientifically, anything that is golf-ball shaped (spherical and having those little dimples) is the most aero-dynamic shape possible, but if you have already built the chassis, then I suggest doing what that other guy said. Also, make sure that the wheels are small, and keep it low to the ground, and add weight to the entire car, as heavy as you can make it, but make sure to put the most weight in the front|||You can put weights on the front of the car.


Then again that's cheating.


Grease its front axles and make sure its properly lubricated.