As a way to help San Francisco Bay Area nonprofits survive the recession as fewer people donate, the Zipcar car-sharing service is letting charity workers drive its cars for free.

The Zipcars are being used by volunteers who help seniors switch their analog televisions to digital, after-school art teachers, environmentalists planting trees, and Big Brothers and Sisters who mentor kids, according to a San Francisco Chronicle story.

Zipcar is the nation's fastest-growing car sharing network, with 250,000 members. It has been around for nearly a decade but has yet to turn a profit. But it's starting to make money in cities such as New York and San Francisco because of the hassle of finding parking.

Fees average $70 a day for the Zipcar.

Here's a Youtube video on how the Zipcar program works: