US federal investigators have expanded an investigation into Tesla Inc (NASDAQ:TSLA) after more than a dozen of cars using its self-driving system crashed into parked emergency vehicles.
The National Highway Traffic Safety Administration (NHTSA) said it will upgrade its investigation into 830,000 Tesla vehicles equipped with driver assistance system Autopilot.
The move is taken before the agency determines a recall.
All four Tesla models - Y, X, S, and 3 - are being investigated, representing about 830,000 vehicles sold in the US, according to media reports.
The probe comes after about a dozen crashes in which Tesla vehicles hit stopped emergency vehicles over a four-year period.
The investigation is focused on Tesla’s Autopilot feature, which is supposed to help drivers navigate roads through artificial intelligence, which detects other vehicles.
A NHTSA investigation has examined about 200 Tesla crashes and is focusing on 16 accidents involving emergency or road-work vehicles, in a probe officially known as an engineering analysis.
"NHTSA reminds the public that no commercially available motor vehicles today are capable of driving themselves," the agency said in a statement, according to CNN.
Tesla's automated technologies are the focus of the NHTSA's work; it reviews whether they make driving less safe, leaving drivers unable to intervene and prevent a collision.
Tesla says its automated driver assistance technology is "designed to assist you with the most burdensome parts of driving", and combines elements of cruise control and lane-keeping assist to maintain a vehicle's position on the highway, though driver participation is still needed.
This system is different from Tesla's Full Self Driving (FSD) beta programme aimed at removing the need for a driver.
Tesla chief Elon Musk has repeatedly delayed estimates of the timeframe when the promised system will be operational.
It is not clear whether FSD crashes are part of the active investigation, although NHTSA said it asked Tesla for information on crashes and non-disclosure agreements.
There were 16 crashes at the base of the investigation between January 2018 and January 2022, which caused 15 injuries and one death, and documents posted on NHTSA's website state forensic evidence indicates that most of the drivers had their hands on the steering wheel before impact and followed the system's instructions.