US Patent 10019857 Hit-and-run detection

A computer in a first vehicle is programmed to detect a collision with a second vehicle, start a countdown timer upon detecting the collision, classify the collision as a hit-and-run with the second vehicle based on expiration of the countdown timer, and upon classifying the collision as a hit-and-run, tag the second vehicle based on at least one of receiving a vehicle-to-vehicle collision broadcast and receiving data from a sensor operable to identify the second vehicle.