Just some thoughts...
You seem to be very close with your code, the kids are going to love it.

Have you seen this?
http://www.picbasic.co.uk/forum/cont...rial-backpacks
What if you did something similar, a "car backpack" ?
Then the parameters that the kids need/want to change to make it their own could be done with the demo version of PBP.
http://melabs.com/pbpdemo.htm
They would not have to learn the whole car code but learn enough to get started.