UPDATE: Tesla tells The Drive that the Model S travels at a maximum speed of 1.06 mph while in Summon mode. Given that, it seems possible to us that the car could have begun moving without being noticed.

A Tesla Model S owner in Utah is claiming his electric car drove itself into a trailer late last month—and he says a malfunction in the car's autonomous driving systems is to blame.

According to KSL News, Model S owner Jared Overton says he parked his Tesla on a street in the town of Lindon on April 29, only to return several minutes later to discover the car had plowed its way under the trailer parked in front of it. The impact was forceful enough to smash the car's windshield.

But when he reported the incident to Tesla, the car maker claimed a review of the car's usage logs revealed Overton was responsible due to inattentive use of the car's self-driving Summon feature. The system, Tesla's response letter claims, “was initiated by a double-press of the gear selector stalk button, shifting from Drive to Park and requesting Summon activation.”

But Overton swears he never activated Summon.