Boxcar2d let you save the genome of the car. I spent months running multiple instances, trying to develop a car to beat those tracks (and the others on the forum).

This one has some amazing features. Hopefully Rafael will give us some way to compete!

It says at the bottom: "Create new world with seed: The same seed always creates the same track, so you can agree on a seed with your friends and compete. :) "

Sadly, that is pretty much the only bit I understood, ish...