Imagine your tire....square, how do you think you drive?

Answer 1

Stationary is right on. The intense power that would be necessary to get those square tires to the point where they could begin to turn enough to go from a standstill and forward over the first corner of the square would make the whole proposition beyond value.

If round wheels had never been an option, we likely wouldn't have the energy crisis we do, as we'd all still be walking or riding animals.

Answer 2

Bumpy at slow speeds, progressively getting smoother as you speed up. When the tires start revolving at above 1500 rpm, you're at a fairly comfortable speed.
Until then, your car will be constantly going up and down at the height level of the tire (unless you design specific vertical suspenders).

Answer 3

you steal another car with round tyres

Answer 4

rough

Answer 5

stationary