A Utah man had his Model S autonomously crash into a parked trailer a couple weeks ago, which has kicked off an interesting back-and-forth between Tesla and the owner. Tesla claims that the car's Summon self-parking feature was activated, and the company seriously came to play here: it has exceptionally detailed logs that it downloaded of exactly what happened in the moments leading up to the crash.

The Verge has had a chance to review the letter sent on May 6th by a Tesla regional service manager to the owner, Jared Overton, which details the warnings in the owner's manual and the vehicle's displays — including reminders that the operator must be prepared to stop Summon if an object isn't detected and a note that it should only be used on private property. (In this case, Summon appears to have been activated on the side of a street.)

It continues, and this is where Overton gets overwhelmed by the hyper-specific data available to Tesla about the collision:

Unfortunately, these warnings were not heeded in this incident. The vehicle logs confirm that the automatic Summon feature was initiated by a double-press of the gear selector stalk button, shifting from Drive to Park and requesting Summon activation. The driver was alerted of the Summon activation with an audible chime and a pop-up message on the center touchscreen display. At this time, the driver had the opportunity to cancel the action by pressing CANCEL on the center touchscreen display; however, the CANCEL button was not clicked by the driver. In the next second, the brake pedal was released and two seconds later, the driver exited the vehicle. Three seconds after that, the driver's door was closed, and another three seconds later, Summon activated pursuant to the driver's double-press activation request. Approximately five minutes, sixteen seconds after Summon activated, the vehicle's driver's-side front door was opened again. The vehicle's behavior was the result of the driver's own actions and as you were informed through multiple sources regarding the Summon feature, the driver is always responsible for the safe operation and for maintaining proper control of the vehicle.

Of course, none of this changes the fact that Summon should be good enough to see a large object that's directly in front of it — but unless the data is completely incorrect, which seems unlikely, Overton clearly broke almost every rule Tesla had in place about operating the feature.

Tesla's official statement about the incident, sent to us by a company spokesperson, echoes the thrust of the letter sent to Overton:

Safety is a top priority at Tesla, and we remain committed to ensuring our cars are among the absolute safest vehicles on today's roads. It is paramount that our customers also exercise safe behavior when using our vehicles - including remaining alert and present when using the car's autonomous features, which can significantly improve our customers' overall safety as well as enhance their driving experience. Summon, when used properly, allows Tesla owners to park in narrow spaces that would otherwise have been very difficult or impossible to access. While Summon is currently in beta, each Tesla owner must agree to the following terms on their touch screen before the feature is enabled: This feature will park Model S while the driver is outside the vehicle. Please note that the vehicle may not detect certain obstacles, including those that are very narrow (e.g., bikes), lower than the fascia, or hanging from the ceiling. As such, Summon requires that you continually monitor your vehicle's movement and surroundings while it is in progress and that you remain prepared to stop the vehicle at any time using your key fob or mobile app or by pressing any door handle. You must maintain control and responsibility for your vehicle when using this feature and should only use it on private property.

Many vehicles have event data recorders — so-called black boxes — that can offer investigators a look into the moments leading up to a car crash, but the granularity of Tesla's data in this case is interesting. Overton claims that he stood next to the car for somewhere between 20 seconds to a minute, which would've been much longer than Tesla's claim that Summon began operating three seconds after he closed the door. For liability reasons, both parties have every reason to shift responsibility to the other party. In this case, though, the difference is that Tesla has a spreadsheet full of numbers and timestamps to back its side of the story.

Letting your Tesla drive itself is a bad idea