Science Buddies: "Ask an Expert"

I have to design a self-propelled car.
It must go atleast 20 meters and my options are very limited.
We cannot use combustion, chemical reaction, or air compression.
We also are limited on resources, we can not use and parts from an actual car and the wheels have to be something that was not designed to be a wheel.
This project must be designed and ready to go by this upcoming wednesday.

If you search Science Buddies and the web generally you will find many ideas for this project. If you have a specific question about designing or building, send us that question.
Good luck.

The idea behind building such a car is fun and very simple, especially with regular household items. If you look up videos on Youtube for "balloon propelled car" or "rubber band car," you'll see that successful cars have already been made with limited materials!