You probably haven't heard of Maven, General Motors' Zipcar-esque car-sharing service, because until recently, it was only available to residents of three Manhattan apartment buildings and people who live in Ann Arbor, Michigan. But Maven is ramping up in a big way today with the announcement that it is either available or coming soon to three major US cities: Chicago, Boston, and Washington, DC.

Maven users have logged over a million miles in the car-sharing service's Chevrolet, Cadillac, and Buick vehicles, which they can rent out at an hourly rate of $6 to $8. That number includes Lyft drivers in Chicago who are renting out Chevy Equinoxes for $99 a week under Maven's Express Drive service. Unlike Zipcar or Daimler's Car2Go, Maven has no annual membership fee, and in some markets, the company's employees will actually deliver the car straight to those customers who request it.

Maven users have logged over a million miles

In Chicago, there are 15 locations where customers can rent Maven cars using an app on their phones. The citywide service will launch in Washington, DC and Boston later this summer. Meanwhile, Express Drive has grown to 200 vehicles in Chicago, and will be available in Boston, DC, and Baltimore by the end of the year.

Building off of its "Let's Drive NYC" program that offered a nascent version of Maven to residents of several apartment buildings in New York City, Maven is also expanding its residential offering. The car-sharing service will be available to Chicagoans who live in the Aqua luxury high-rise apartment in the city’s Lakeshore East neighborhood, as well as residents of the Hepburn, a 195-unit luxury apartment opening in June on the grounds of the Washington Hilton, located in DC’s Kalorama neighborhood. The service will also be available in Boston later this year.

In Ann Arbor, where the service has been available since January, over 1,500 users have signed up to rent out one a Chevy Volt, Tahoe, Spark or Malibu (the Volt is the most popular). "As we continue to expand into key cities, more customers will see how Maven can provide next-gen freedom by seamlessly connecting them with people and places that matter," said Julia Steyn, GM vice president of urban mobility and Maven, in a statement.