WASHINGTON (AP) — Tesla shouldn't be calling its partially automated driving system Autopilot because the cars can't drive themselves, the top U.S. transportation official says.

Transportation Secretary Pete Buttigieg says he's concerned about Tesla's marketing of the system, which is under investigation by his department in connection with crashes that have caused at least 14 deaths.

"I don't think that something should be called, for example, an Autopilot, when the fine print says you need to have your hands on the wheel and eyes on the road at all times," Buttigieg said in an interview with The Associated Press.

The National Highway Traffic Safety Administration, an agency within Buttigieg's department, has sent investigative teams to more than 30 crashes since 2016 in which Teslas suspected of operating on Autopilot or its more sophisticated automated Full Self-Driving system have struck pedestrians, motorcyclists, semi trailers and parked emergency vehicles.

The probes are part of a larger investigation by the NHTSA into multiple instances of Teslas using Autopilot crashing into parked emergency vehicles that are tending to other crashes. The NHTSA has become more aggressive in pursuing safety problems with Teslas in the past year, announcing multiple recalls and investigations.

Tesla, based in Austin, Texas, didn't immediately return messages left Thursday by the AP seeking comment.

Autopilot can keep a car in its lane and away from vehicles in front of it, while Full Self-Driving can take on most driving tasks. But in each case, Tesla tells owners they must be ready to intervene at all times.

Buttigieg said the Transportation Department will hold Tesla or any other company accountable for complying with federal safety standards. "We call balls and strikes," he said. "I view it as something where it's very important to be very objective. But anytime a company does something wrong or a vehicle needs to be recalled or a design isn't safe, we're going to be there."

In the Wednesday interview, Buttigieg said that self-driving vehicles have enormous potential to reduce the nearly 40,000 U.S. roadway deaths that happen each year, a level that he called unacceptable. But he said the technology has not been proved yet. "It's far from automatic that it's going to meet that potential," he said. "That's what we're trying to shape here at the Department of Transportation."

The NHTSA also is looking at Tesla's Full Self-Driving system. In February, the agency pressured Tesla into recalling nearly 363,000 vehicles with the software because the system can break traffic laws. The problem was to be fixed with an online software update.

Tesla CEO Elon Musk has said he expects to have fully autonomous vehicles this year, a pledge he has made for several years. "The trend is very clearly toward full self-driving," Musk said in April. "And I hesitate to say this, but I think we'll do it this year."

The system is being tested on public roads by as many as 400,000 Tesla owners. But the NHTSA said in documents that the system can make unsafe actions such as traveling straight through an intersection from a turn-only lane, going through a yellow traffic light without proper caution or failing to respond to speed limit changes.

The NHTSA also has opened investigations during the past three years into Teslas braking suddenly for no reason, suspension problems and other issues.

Buttigieg wouldn't comment specifically on the pending investigations. "Both outside bodies, states and other regulatory entities on the marketing side, and us from a vehicle safety perspective, are always paying attention," he said.

No vehicle on sale today can drive itself, he stressed, saying that drivers must pay attention in all cases.

The Justice Department also has asked Tesla for documents about Full Self-Driving and Autopilot.

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Krisher reported from Detroit.