The company reported only minor fender benders and scrapes in Pittsburgh. Bad driving was caught on tape during the cars’ debut in San Francisco and one was involved — but not at fault — in a crash in Tempe. Wagner suspected Uber engineers are looking at more than just the crashes or bad driving caught on tape. Any time a piece of hardware or software failed should be examined, even if the failure lasted just for a few seconds and nothing happened, Wagner said.

“Even over a million miles, effects like that might not result in full-blown collisions,” Wagner said.