Monday's verdict by a Fort Lauderdale federal jury in Florida came in what lawyers for the teenager's parents James and Jenny Riley called the first trial against Elon Musk's company over an accident involving its vehicles.
Jurors found Tesla negligent for deactivating a "speed limiter" that the parents had installed to keep their son Barrett from driving too fast.
Barrett Riley was driving at 187kmh, on a curve with a posted 40kmh speed limit, on May 8 in 2018, when he lost control of his 2014 Model S while trying to pass another vehicle, causing a fire.
Another passenger also died while a third occupant survived.
The jury found Tesla 1% negligent, Barrett Riley 90% negligent, James Riley 9% negligent and Jenny Riley not negligent in Barrett Riley's death.
It said James and Jenny Riley suffered a respective $US4.5 million ($NZ7.2 million) and $US6 million of damages for pain and suffering, which the judge can reduce based on the negligence findings.
Tesla's lawyers did not immediately respond on Tuesday to requests for comment.
Riley's parents said the crash occurred after Tesla, without their knowledge, disabled a device capping the Model S's speed at 137kmh.
They also said a design defect in Tesla's lithium-ion battery cells and battery pack contributed to the fire.
Tesla said Barrett Riley's recklessness caused the crash, and his parents should have taken away the keys after his March 2018 speeding ticket for driving at 180kmh.
It also said Barrett Riley tricked its technician into disabling the speed limiter, that the battery design was not defective.
In a statement, the Rileys' lawyer Curtis Miner said they were pleased with the negligence finding, and hoped the case would help prevent other accidents and save lives.
Tesla has faced a variety of lawsuits and regulatory probes over crashes tied to its Autopilot feature. That feature was not at issue in Barrett Riley's crash, court records show.
