America’s road safety regulator is looking into Tesla’s newest robotaxi just a day after it began carrying passengers.

“NHTSA is in contact with Tesla and is evaluating the situation,” a spokesperson for the National Highway Traffic Safety Administration said, according to Reuters.

The service began on Thursday in limited areas of Austin. Ashok Elluswamy, Tesla’s head of AI, said it is open to the entire public, although the company has not said when it will start charging fares.

The agency is looking at the vehicle itself rather than the software. The Cybercab is a two-seater with butterfly doors and no steering wheel, pedals or mirrors, all of which federal motor vehicle safety standards generally require a car to have.

Tesla has not announced an exemption covering those requirements. The usual route for a vehicle without manual controls is a formal NHTSA exemption, which is capped at a small annual volume, and nothing of that kind has been made public.