(Gerald Martineau for The Washington Post)

Looking for some company — and maybe a little cash — the next time you drive? A new ride-sharing service wants to help.

SideCar, an app-based service that is basically a 21st-century version of carpooling, arrived in the District on Friday.

The premise is simple: Travelers can use the app to hitch rides with nearby drivers, while drivers who sign up can get paid for giving these rides. There’s no set fee, so passengers can pay the drivers any amount. (The app does come with a suggested donation, but riders can pay more or less if they want.)

Of course, the idea of getting into an unfamiliar person’s car raises some obvious questions. But the company says it takes safety seriously.

“Every time you get into a taxicab you get into a stranger’s car,” said Nick Allen, the company’s co-founder. “And we go through a lot of measures to make sure it’s safe.”

Allen said that all drivers are given a “full background check,” which includes looking for any criminal history. SideCar also verifies that drivers have license, insurance and registration. Drivers are also given additional training, and all rides are tracked by GPS.

Riders also have the option to pick specific drivers or, if they want, to block some drivers from seeing that they need a lift.

SideCar began offering rides in San Francisco, where the company is based, and in Seattle in 2012. It began service in Austin, Los Angeles and Philadelphia last month, and expanded into New York, Boston and Chicago last week. D.C. represents the last bit of expansion for now, Allen said.

The rollout hasn’t been without any headaches for the company, which raised $10 million in financing from Google Ventures and Lightspeed Venture Partners last November. SideCar sued Austin recently, following a cease-and-desist letter from the city accusing the company of running an unlicensed taxi service, according to the Austin American-Statesman.

After SideCar arrived in Philadelphia, the city responded by impounding and fining vehicles. Last year, a California commission fined SideCar and similar services for lacking the proper permits.

The notion of an app-based car service encountering problems with local officials obviously sounds familiar in the District. Uber, the car-dispatch app, had repeated problems with local officials before gaining legislative acceptance in December.

Allen said that Uber and SideCar aren’t really comparable, because Uber is a car service that charges a fare. But he said these early hiccups are just a matter of regulators trying to figure out how to properly oversee these services, which don’t always fit into preexisting categories.

“They think we’re a taxi or a limousine, and we’re actually very different,” Allen said. He said it’s more like an app-based slug line.

For the first few weeks, SideCar will only be available on Fridays and Saturdays between 5 p.m. and 3 a.m. the following morning. After that, it should become available every hour of every day of the week — as long as drivers are available.

“It’s just another option in transportation,” Allen said. “There’s buses and there’s trains and taxis and personal automobiles, and we are another option.”

The app is available on Android and Apple. You can follow SideCar in D.C. on Twitter at @SideCarDC.

What do you think of SideCar? Does it sound like something you might use, or are there potential issues that may keep you away? Let us know in the comments below.