Algodoo

A single wheel car like my first one, but this one has an air-friction stabilizer instead. You can make it go up a wall at any angle, even 90 degrees.
You can also make it move at almost any speed, and it won't jitter around (unless you get too far away from the center of the simulation or whatever).

Just about the only thing that I can think of that this car doesn't do well, is jumping. You can't jump, or else the car will stop in the air and fall very slowly.

OH, one crucial piece of information for you. The air stabilizer bar collides with B, cuz it has to collide with something. You can make it collide with anything you want and it'll work ('cept for A). I just made it collide with B.

NEWFOUND INFORMATION: I figured out a little bit ago that if you turn air off, this car can still roll the way you tell it to. With air off, it's faster, and it can jump, but it's less powerful.
It can only make it up about 45 degrees.