“It’s just surreal,” General Motors CEO Mary Barra says while testing one of the company’s driverless cars in San Francisco, calling it a highlight of her career.

Barra took the ride last week in a retrofitted Chevrolet Bolt EV with Kyle Vogt, founder and interim CEO of Cruise, the automaker’s majority-owned autonomous vehicle subsidiary. The self-driving vehicle, called Tostada, is one of a fleet of driverless Cruise vehicles currently operating at night in San Francisco as the company prepares for commercialization of the operations this year.

“That was incredible,” Barra says in video posted on the Cruise’s YouTube page. Later adding, “This is going to change the way people move in such a positive way … I’m over the moon.”

Vogt stepped in as CEO after Dan Ammann, a former GM executive who was leading Cruise, was reportedly ousted over internal disagreements with Barra.

Autonomous vehicles are viewed as a potential multitrillion dollar market. GM expects the operations to potentially contribute up to $50 billion in annualized revenue by the end of this decade. However, commercializing self-driving vehicles has been far more challenging than many predicted even a few years ago.

The ride was Barra’s first in an unmanned vehicle without a safety driver.

Cruise late last year began testing a fully driverless fleet of vehicles without human backup drivers. In November, Cruise posted a video of Vogt during his first driverless ride in San Francisco.

The nearly three minute video with Barra also includes GM President Mark Reuss and Craig Buchholz, senior vice president of GM’s communications, in another self-driving vehicle called Disco.

Reuss calls the drive “unbelievable,” discussing the performance of the vehicle and its potential impact on society, including senior citizens such as his 85-year-oldfather, Lloyd Reuss, who also served as president of the automaker during the early 90s.

GM acquired Cruise in 2016. Since then, it has brought on investors such as Honda Motor, Softbank Vision Fund and, more recently, Walmart and Microsoft.