If you call an uberX in San Francisco today, there's a good chance your ride won't require a driver.

Starting Wednesday, riders who request an uberX in San Francisco will be matched with a self-driving Uber (if one is available). After a successful four-month trial of self-driving cars in Pittsburg, Pennsylvania, the SF-based company is bringing the technology back to the Bay Area with a fleet of Volvo XC90s that don't require a driver.

"With its challenging roads and often varied weather, Pittsburgh provided a wide array of experience," said Anthony Levandowski, head of the Advanced Technology Group, in a statement. "San Francisco comes with its own nuances including more bikes on the road, high traffic density and narrow lanes."

If you're thinking of calling one right now to check it out, know that Uber also decided to forgo a testing permit to test drive their new fleet on San Francisco roads, citing that there will be a person in the car to monitor it, so...don't forget to wear your seatbelt!

[UPDATE] The California DMV has released a statement, which includes a warning to Uber:

"We have a permitting process in place to ensure public safety as this technology is being tested. Twenty manufacturers have already obtained permits to test hundreds of cards on California roads," the DMV said. "Uber shall do the same."

Uber insists that its self-driving cars don't fall under the DMV's regulations because they require a person to monitor them. They have no plans to apply for a permit.