PALO ALTO — A Los Altos planning commissioner was arrested on suspicion of driving under the influence of alcohol early Friday after he fell asleep behind the wheel of a Tesla Model S and managed to travel about seven miles on Highway 101 without crashing, according to the California Highway Patrol.

It appears the driver had the Tesla driver-assist, or autopilot, function engaged at the time he was pulled over, but the CHP needs to finish its investigation before making a final determination, Officer Art Montiel said.

About 3:35 a.m., a CHP officer noticed a gray Tesla Model S driving south on Highway 101 near Whipple Avenue in Redwood City at about 70 mph, said Montiel, adding that the officer who pulled alongside the car noticed the driver appeared to be sleeping.

The officer got behind the Tesla and turned on his patrol car’s lights and siren in an attempt to wake up the driver and pull him over.

When the driver did not respond, the officer drove in front of the Tesla in an effort to slow down the vehicle. The officer believed that if the Tesla’s driver-assist function was engaged, the car would slow down when it sensed a vehicle in front of it, Montiel said.

At the same time, another officer was running a traffic break behind the Tesla to keep other motorists from traveling past it.

The Tesla eventually came to a stop in the No. 3 lane north of Embarcadero Road in Palo Alto, about seven miles from where the dozing driver was first spotted. Officers woke up the driver, put him in a patrol car and took him to a nearby Shell gas station.

Another officer drove the Tesla to the gas station, where it was towed.

The driver, identified as Alexander Joseph Samek, 45, of Los Altos, failed a field sobriety test and was arrested on suspicion of driving under the influence, Montiel said. Samek is a real estate developer serving his first term on the Los Altos Planning Commission, which advises the city council on planning and transportation issues, according to the city website. He was appointed chairman of the panel last month.

Montiel stressed that drivers need to be able to control their vehicles.

“What we know is that people who are using driver-assist mode need to know they are responsible and aware of their surroundings while the vehicle is in motion,” he said.