SAN JOSE, Calif. – Donnie Fowler owns a 2006 Saab that’s fully paid for, but he almost never drives it. A self-employed consultant who lives in San Francisco, he often works from home and takes public transportation to most of his meetings.

But his car does not sit idle — it’s out on the streets earning money. Fowler rents out his Saab for $8 per hour via Getaround, one of several car-sharing networks that have sprouted in his area. Since joining Getaround in the fall, Fowler has earned more than $800 — money that goes straight into his infant daughter’s college fund.

Photos of his Saab are on Getaround’s website, along with a description: “sporty, powerful and dependable four-door car with bike rack for two,” along with reviews from renters who have driven it.

“At first I was pretty wary,” Fowler said. “I wondered if it was going to get wrecked. Are they going to smoke? What’s my insurance exposure?”

But he said Getaround carefully screens renters, and that the renters have been friendly and considerate.

“They thank me and feel like they know me,” he said. “One guy washed my car for me, which is not part of the deal.”

Getaround is one of several San Francisco Bay Area “peer-to-peer” car-sharing services — others include RelayRides, PATS CarShare and Spride — where car owners rent their personal vehicles to other drivers. Car owners have found the services a relatively hassle-free way to make extra money, while renters say they offer a convenient alternative to traditional car-rental companies.

The car-sharing services vary in prices and policies — PATS requires drivers to be at least 21 — but all were founded on the same realization: Most cars sit unused much of the time, and many two-car families don’t need both vehicles on weekends.

Getaround, a San Francisco-based startup in the midst of raising its first round of venture funding, launched in March 2011 and has about 800 cars in its portfolio. Most of those cars belong to Bay Area drivers, but Getaround is also active in San Diego and Richmond, Calif.; its next market is Portland, Ore.

“Our typical user is someone who doesn’t own a car — like someone needs a car to make a trip to Ikea,” said Avery Lewis, Getaround’s head of product, in an interview. “But we also have travelers coming in from Europe who want to rent a car for two months. There’s high demand for electric vehicles — people are really interested in driving them.”

Car owners can set their own price, and Getaround takes 40 percent of that. Its fee covers insurance, roadside assistance and a security check, which includes searching Department of Motor Vehicles records of potential renters. Renters are also required to have active Facebook profiles. Getaround has found Facebook to be a good source of identity verification.

Getaround owners can meet renters in person to hand over their keys, or make arrangements via text message. Hardware called a “Carkit” makes it possible for renters to unlock and lock a car using a smartphone. It also includes GPS tracking, so owners know where their vehicles are at all times.

One of the big appeals of car sharing for many renters is that money is directed to individuals instead of large agencies.

That’s one of the reasons Jeff Tatro, who regularly commutes from Oregon to San Jose, is an avid fan of PATS CarShare, a tiny car-sharing startup run by Patrick Mahan. He started the service in October and has just four cars in his fleet.

Tatro works at an insurance brokerage in San Jose. But he moved to Salem, Ore., 12 years ago, seeking a slower pace of life for his family. He largely telecommutes but comes to San Jose every other week. Mahan gives him a good weekly rate and often delivers a car to him at work.

“Rental car agencies get really expensive, and they have a lot of hidden costs and fees,” said Tatro, who takes whatever car PATS has on hand.