Except for some very minor sloping for drainage, those places are usually very close to level. Now maybe the concrete did slope away a little steeply from where it was parked toward the street to accomodate the downpours that area can get, but you wonder what could have provided the energy to overcome inertia and friction. Tires must have been full, fer sure.

In another area of the country, a small plane with the pilot hand-spinning the prop took off by itself about two months ago. The pilot had too much throttle, no chocks, and couldn't get back in, watched it roll off and fly away. It crashed not too long after that.

There's a story in that AA plane rolling off. Wonder if we'll ever hear it.

Arf