The square wheel thing was definitely fun to watch. I certainly expected the ride would smooth out once they got going fast enough, but I wasn't sure the tires would actually hold up LONG enough for that (and they very nearly didn't).
Of couse the catch appeared to be that the faster you go, the less traction you have, because the tires are skipping along and only contacting the ground at those 4 points.
I do wish they had tried the slower approach on the hill though. The tires might have functioned more like a tractor tread than the way they did it, where the spinning tires just dug giant holes in the dirt.