This will sound a little odd in description, but I am not sure about how to refer to it.

Would it be possible to increase the height of bricks that ground vehicles can go over?
At the moment they can just barely get over 0.333333 brick high steps, and generally only at high speed, and it would be nice if they could get regular steps, say 1 brick high, like regular minifigs, given that they can drive up near-vertical cliffs, etc, and it would make it tons easier to make racetracks for them.

Basically, it'd be nice to have the maneverability of the vehicles in Halo shown here - that is, you can drive a jeep up stairs and around some rough terrain with speed reduction and some difficulty, but you can get over some quite large height differences, whereas the Lego Cart felt more like you were sliding a flat-bottomed brick around and it was unable to get over the slightest most subtle incline.

That's about all I can think of.

presumably the wheel collision meshes need to be big enough to clear the vehicle collision mesh.

Ideally, vehicles ought to be able to clear stairs either 2 or 3 studs deep.

I guess the goal would be to give the truck the maneuverability it looks like it should have.

What about cars that can hang from the ceiling? would be nice for Loop the Loopes.

Are those......eyeteeth? </badpun>