The sharp rise in the miles tested on California’s roads suggest that Apple has been quietly ramping up its autonomous ambitions. Records show its cars were tested over 450,000 miles in California between December 2022 and November 2023 — more than tripling from the year before, and the biggest jump among companies with the most testing in the state.

While it’s unclear what the company hopes to accomplish with its cars, Apple is pouring resources into a tumultuous industry in which others have lost permits and faced lawsuits, recalls and public frustration over erratic behavior from some of the cars. It’s a unique thing for Apple to test a product in the public eye where it could be subject to intense public and regulatory scrutiny, as the company typically tightly controls its image and keeps new products under wraps until they are ready for market.

Still, experts see Apple’s increased testing in California as a vote of confidence in the potential of automated driving — despite a tumultuous year in which officials here have called for more regulation and scrutiny on the fledgling technology. The company wields enormous power over consumers’ lives, and its technology — from smartphones to computers — has changed the way that people live and work.

“It is pretty big market validation,” Ed Walters, who teaches autonomous vehicle law at Georgetown University, said of Apple’s increased testing. “People over focus on the [self-driving car] accidents, and every day that there is a highly publicized autonomous vehicle accident, hundreds [of crashes occur] behind the wheels of human-piloted cars.”

Records show Apple is moving more slowly compared with other leaders in the industry: The company has been working on autonomous vehicles for years but still only has permits to test in California with a human driver. The current leader in the space, Alphabet-owned Waymo, has been offering fully driverless robotaxi rides to customers in San Francisco for months.

Apple has also reportedly delayed its debut date for its car technology, according to Bloomberg News, and is no longer trying to create a fully self-driving vehicle. Instead, it is reportedly working on creating driving-assistance features, like those popularized by Tesla. Those features, however, have been linked to dozens of fatal and serious crashes and have also been the subject of intense public scrutiny, lawsuits and recalls.

Apple declined to comment.

Overall, autonomous car companies tested more than 9 million miles during the last reporting period on California roads last year. That’s nearly 4 million more miles than 2022, according to state Department of Motor Vehicles data analyzed by The Washington Post. Nearly two-thirds of the miles driven in the 2023 reporting period — including those from Apple — were with so-called safety drivers, who were ready to take over whenever the technology made a mistake or needed assistance. The rest were fully autonomous with no human driver present.

A total of 38 companies have received permits to test in California, according to the DMV. Waymo, Amazon-owned Zoox, General Motors-owned Cruise, Apple and Nuro were among the companies that totaled the greatest number of miles for their autonomous vehicles last year, according to the data. Waymo, which is owned by Google, totaled more than 4.8 million miles in 2023.

The next closest company, Cruise, had more than 2.6 million miles, while Zoox registered more than 700,000.

As both Waymo and Cruise aggressively expanded in San Francisco, they caused major headaches as their cars proliferated around the city. Both companies have cited self-reported data that their robot cars have a superior track record to human drivers, but the cars have also disrupted traffic by stopping short or suddenly breaking down and have also disrupted emergency scenes.

Despite these issues and sharp objections from city leaders, California state regulators granted both companies permits to offer 24/7 robotaxi service in San Francisco last summer. But Cruise lost its permits just a few months later, after a human-driven car hit a jaywalking pedestrian and flung her into the path of the Cruise vehicle. The robot-driven car failed to detect the woman underneath the car and dragged her at 7 mph for about 20 feet, causing grave injuries that hospitalized the woman for weeks.

That crash is now the subject of two federal probes by the Justice Department and the Securities and Exchange Commission. Cruise also pulled its entire driverless fleet around the country and issued a voluntary recall of 950 of its vehicle nationwide after the collision.

The San Francisco city attorney has also filed a lawsuit against the state commission that allowed Waymo and Cruise to expand in San Francisco despite causing a pattern of “serious problems” on the streets. The city is asking the commission to reconsider the permits for Waymo and also “develop reporting requirements, safety benchmarks, and other needed public safety regulations” for the rapidly evolving industry.

Meanwhile, as Waymo and Cruise largely take the spotlight in California, companies like Apple have been largely operating without any serious, publicly reported incidents, according to DMV crash reports. But that’s probably because Apple is still only allowed to test its cars with a human behind the wheel who is fully alert and ready to take over at any time, and publicly disclosed data doesn’t necessarily reflect the extent of issues that the cars may experience on the roads.

Walters, the Georgetown professor, said the more companies ramp up their testing, the more incidents they will naturally cause. But he said the safety benefits that could come with more automated cars or driving-assistance features are too critical to slow the industry down.

In 2023, “there were definitely some setbacks, but there was also a lot of progress,” Walters said. “In 2024, we may have machine-learning breakthroughs in autonomous vehicles that will catapult us to capacities that we can hardly imagine at the beginning of the year.”