A former Twitter engineer got a Waymo robot taxi to give her a 6.5-hour ride around San Francisco. Here's what happened.

• Sophia Tung rode in a Waymo for 6.5 hours around San Francisco.
• She says she would've ridden longer, but the Waymo's battery was running low.
• A Waymo spokesperson says it was one of the "longer personal trips" by a public passenger.

A software engineer managed to make a Waymo drive her around San Francisco for 6.5 hours — marking one of the longest rides ever taken by a paying passenger.

Sophia Tung, a former Twitter software engineer, told Business Insider that Waymo had given her a promo code for a free ride after the engineer set up a livestream that pointed to a Waymo depot, capturing the early morning honking from the cars that were waking her and her neighbors. The company has said that it resolved the July issue.

For the inconvenience, Tung said Waymo gave her a few promo codes that could be redeemed for a free ride. But she noticed the offer didn't come with any value cap and came to a realization.

"Well, clearly the best deal would be if I took the longest ride possible," Tung said.

Tung said her initial idea for the challenge was to stay in a Waymo for 24 hours. But even without the limitations of a human driver, the Waymo still had its own restrictions.

Screenshots shared with BI show that Tung managed to stay in one Waymo for 6.5 hours, traveling 83 miles within San Francisco's dense grid. Sandy Karp, a spokesperson for Waymo, verified that Tung's ride was among the longest ever taken by a member of the public. Karp also said Waymo is "exploring" ways to set certain limits on rides.

Here's how Tung did it.

Journey prep

Even before she began her challenge, Tung said she knew it would be a "miracle" if she reached close to 12 hours inside the car.

The engineer recognized that the Jaguar I-PACE, Waymo's choice of electric vehicle for its autonomous fleet, had a limited range. Jaguar advertises a range of up to 246 miles for the I-PACE.

That doesn't account for the cameras, GPUs, and "beefy computers" attached to Waymo's fleet that likely take up battery power, Tung said.

Still, Tung said she prepared for a 24-hour haul by carrying multiple cameras with extra batteries, making a bathroom run before her trip, and eating high-carb, low-dairy snacks that would not overstimulate her digestive system.

The Waymo was also limited to local roads within the city limits of San Francisco, which is less than 50 square miles. The company also restricts riders to four stops before passengers must step out and request a new ride.

To circumvent this, Tung said she would edit her journey mid-ride to direct the Waymo to different parts of San Francisco.

Just before the Waymo reached a stop, Tung said she would input a new destination on the other side of the city.

Karp said the company is now "exploring" limiting the number of times users can edit their journey.

Waymo's limit

A screenshot shared with BI showed that Tung's ride began around 6:30 a.m. and ended around 1:10 p.m.

The engineer had the Waymo drive by landmark spots and pick up a friend for a guest on her vlog. To limit the number of stops she would rack up from picking up and dropping off her friend, Tung said her friend crawled through the window so the Waymo wouldn't register a stop as it does when the door is opened.

"He did that in front of a Chick-fil-A, and people were like, 'What the heck?'" she said. Karp, the Waymo spokesperson. said this act would violate the company’s terms of service.

What surprised Tung most was the limited number of issues she ran into during her long ride.

Tung said it was a mostly smooth experience, save for a few slightly tricky situations when driving on narrower roads, running into a dead end, or dealing with aggressive drivers cutting off the Waymo.

"I honestly thought that there would be more interventions from the remote assistance people," she said. Tung added that there was one instance when Waymo appeared to call for remote assistance before it seemed to cancel the call and figure out the problem.

Tung said she could've gone for a longer ride.

According to Tung, her journey was limited because Waymo did not connect her with a fully charged car. She said all the cars she requested had a charge of 80% or less.

Karp wrote that the company adopted the industry standard of charging to 80% to maximize the life span of the car's battery.

When the car reached an estimated range of 20 miles left, Tung said the Waymo ended the ride.

"I certainly didn't realize how tired the ride was making me feel until I stepped out of the car after six and a half hours," she said. "My legs sort of just gave out."

Karp said it was one of the "longer personal trips, but the Waymo Driver can operate for far longer without a disengagement."

As a San Francisco resident, Tung said Waymo isn't her main mode of transportation. But she'll give the company some props.

"Having witnessed all of that, I'm more inclined to trust Waymo's driving more than even my own driving," she said.