Electric Vehicle

Hey all, I am working on a project for Science Olympiad where I need to create a vehicle that runs on an electric motor and batteries and that travels a certain distance. I was thinking the easiest thing to do would be have 4 press buttons of different colors and create numerous combinations of the buttons. Each combo will be assigned a specific distance to it. I was wondering if anyone has a more basic idea for this project. If so, please let know, I would be glad to hear of different ways to work on this. And it would be great if I could get some quick responses as well since I am pretty short on time.
Thanks a lot,
Sagi Ravid.

Your description is not sufficiently detailed to make alternative suggestions practial (or polite).

If you only need one "certain distance" (as your first sentence implies) why do you need any buttons?

If you need to choose between preset distances then buttons can be used for that.

...R