How could I make the toy car on a ramp experiment better?

Question

This would be for our science fair. My teacher would not allow us to choose this because she thinks its too simple and I agree with her.

Answer 1

what exactly is the experiment..?

Answer 2

Do you mean how to make the car better, or how to make the experiment better?

The car will accelerate slightly faster if it has small wheels with little mass and good bearings. The experiment will be better if you have automatic graphic recording of position v time.  

Answer 3

Reduce the weight of the model as much as possible and make sure the wheels are aligned and as free of fiction as possible.