It was about 3:30 in the morning, and the car was cruising south on Highway 101 in Redwood City, when the California Highway Patrol unit pulled alongside and observed the inexplicable.

The driver was asleep.

The officers eased behind the car, which was doing 70 mph, and hit the flashing lights and siren. No response.

It was then that the officers, whose names have not been released, invented what the CHP says is a new maneuver in highway traffic control.

Deducing that the Tesla Model 3 was running on Autopilot, the officers called for backup and prepared to employ a stratagem.

After a second unit caught up to block any traffic coming from behind, the original car sped up to get in front of the Tesla, then gradually slowed to a stop.

The cameras and computer algorithms of the vehicle’s self-driving system did their job, slowing to avoid ramming the officer’s car.

Several miles from the first contact, the Tesla slowed to a full stop just north of the offramp at Embarcadero Road.

According to the report on the Nov. 30 incident released by the CHP, the officers had to knock on the window to rouse the driver, identified as Alexander Joseph Samek, 45.

While one officer took Samek to a nearby gas station to conduct a DUI investigation, the other drove the Tesla off the freeway.

Samek was arrested on suspicion of driving under the influence and transported to San Mateo County Jail.

The report said the CHP could not confirm that the vehicle was on Autopilot, but “considering the vehicle’s ability to slow to a stop when Samek was asleep, it appears the ‘driver assist’ feature may have been active at the time.”

On its website, Tesla says that all of its vehicles including Model 3 “have the hardware needed for full self-driving capability at a safety level substantially greater than that of a human driver.”

However, there have been several crashes involving Teslas in Autopilot mode, and the company instructs drivers to keep their hands on the wheel at all times.

Officer Art Montiel, public information officer for the CHP’s Redwood City office, said there was no training for the situation the officers encountered and attributed the outcome to their “quick thinking.”