The US auto safety regulator has asked Tesla for more details on its planned automated taxi service in Austin, Texas, focusing on how the service uses Tesla’s “Full Self-Driving”, or FSD, offering that is the subject of an ongoing investigation by the agency.

In a letter sent to Tesla that was made public on Monday, the National Highway Traffic Safety Administration (NHTSA) said it had become aware from Tesla’s “public statements” that it was planning to use a driving-assistance system based on FSD in the “Robotaxi” service, planned for launch in June, and requested more details on the service and how it would perform in poor weather.

The NHTSA’s existing FSD probe, launched in October, focuses in part on how the system found in 2.4 million private Tesla vehicles performs in reduced visibility conditions, after four reported collisions including a 2023 fatal crash.

Reduced visibility

The letter asks how many vehicles will be used as robotaxis, the expected timetable for such vehicles to become available for control by people or organisations other than Tesla and whether the vehicles will be monitored or supervised in real time.

The agency asks how Tesla plans to ensure safety in reduced visibility conditions such as sun glare, fog, airborne dust, rain, or snow and what will happen if such conditions arise during a ride.

It asks for details on the vehicles’ sensors, use of cameras, and whether the systems comply with any industry standards for automated driving systems.

Tesla has said the Robotaxi service will be based on what it calls “Supervised FSD”, but has given few details about its plans.

The company has until 19 June to respond or faces up to $27,874 (£21,152) per violation per day.

According to a filing in May of last year that was made public in November, the NHTSA expressed concerns to Tesla over FSD months before it launched its official investigation in October.

The agency raised concerns with Tesla that the feature was being promoted in a way that suggested FSD could be used as a robotaxi and did not need driver attention, the NHTSA’s filing said.

‘Requires persistent attention’

In a 14 May email, NHTSA told Tesla its social media messaging could encourage viewers to consider the feature as a robotaxi “rather than a partial automation/driver-assist system that requires persistent attention and intermittent intervention by the driver”.

In December 2023 Tesla agreed to recall nearly its entire base of US vehicles to add new features to the Autopilot driver-assistance feature to make it more difficult for users to bypass controls intended to ensure they are paying attention.

The agency is still reviewing whether Tesla’s updates were sufficient.

While Autopilot comes with every Tesla vehicle, FSD is a paid service that adds features such as self-parking, automatic lane changes and traffic navigation.