Tesla in Autopilot sped up before Utah crash

Data from the Model S electric vehicle show it picked up speed for 3.5 seconds shortly before crashing into a stopped firetruck in suburban Salt Lake City, the report said. The driver manually hit the brakes a fraction of a second before impact.

The driver of the vehicle, Heather Lommatzsch, 29, told police she thought the vehicle's automatic emergency braking system would detect traffic and stop before the car hit another vehicle.

She said she had owned the car for two years and used the semi-autonomous Autopilot feature on all sorts of roadways, including on the Utah highway where she crashed, according to the report.

Lommatzsch said the car did not provide any audio or visual warnings before the crash.