A simple car, but with squishy wheels. You can throw it, crunch it, even drop it from miles high, and it'll be fine. It drives through a ball pit like it's solid ground (mostly), climbs up about 40 degrees, and much, much more probably!
Seriously though, the only problem with the wheels that I can think of, is they have to be connected to the car somehow, so one of those cross-bars that you see is connected to the body by a center hinge for each wheel.
The problem with that, is that the car has one ridged bar per wheel, and the rest squish, so that makes it bounce a bit at high speeds.
I hope you have fun with this wheel design. I know I did!
And if this design was somehow created by somebody else, I swear that I made it up on my own.