idea 2: for the accelerate and stop controls.

This idea is to use a container filled with some liquid (most likely water). The container is situated on top of a pressure sensor. So the heavier the container (the more water is inside, the faster the car goes. And the lighter the container (the less water there is ) the more the car slows down. The player would use a big syringe to either add or take out water according to how fast they would want the car to go.

Below is a quick sketch of this idea: 

We already tested out an Arduino code with a pressure sensor which worked.

The idea would be to use JoyToKey or a similar program in order to compute the oscillation of pressure into a computer key stroke.