THE LAST CAR

33-year-old Sarah Fidelibus bought was in 1991 when she was in high school. It was a Toyota Tercel that in recent years started breaking down regularly, resulting in mounting repair bills. The costs and frustrations seemed excessive considering that Fidelibus, who teaches English composition at San Francisco State University, was only driving her car 70 miles a week. When the car failed a smog inspection last year, she finally gave up.

A state-run program that buys vehicles dubbed "gross polluters" paid Fidelibus $1,000 for the beaten-down Tercel. In January she used $300 of that windfall to join City CarShare, a nonprofit car-sharing company in the San Francisco Bay area. (The $300 was for a fully refundable security deposit.) Now when she needs a car say, to transport teaching materials from her apartment to her office she reserves one online, picks it up at a "pod" near her home and drops it off whenever she's done.

By not owning a car, Fidelibus says she's saving about $100 a month in insurance and fuel costs and even more in maintenance. "The biggest savings of all, though, is in avoided stress," she says. "I love that I have ready access to a well-maintained vehicle, but that I'm not the one maintaining it."

A growing number of Americans are starting to think like Fidelibus. Consider this: The average American household spends 18% of its expenditures on owning and operating their cars, according to the Bureau of Transportation. Plenty of car owners, especially in urban areas where public transportation is readily available, don't even use their vehicles enough to warrant the monthly insurance payments, let alone the cost and effort involved in upkeep like oil changes, replacing the air filter or buying new tires.

Car-sharing is the perfect compromise for people who find themselves on foot more than behind the wheel. After paying an application fee (typically $25), members usually pay an annual membership fee of roughly $35 to gain access to the company's fleet of cars. Cars are reserved online sometimes with as little notice as an hour and then picked up at one of several designated parking spots in a neighborhood. Hourly rates range from $3 to $10 and include gas, maintenance and insurance.

Popular in Europe for the past few decades, car-sharing is starting to gain momentum in the U.S. As of last January, there were 18 car-sharing programs here, boasting 134,094 members, according to Innovative Mobility Research, a group that researches environmentally-friendly transportation alternatives. Those members shared 3,637 vehicles roughly the equivalent of 37 users per car.

ZipCar and Flexcar are the most well-known car-sharing companies, but other, more localized companies like Philadelphia's Philly CarShare, Madison, Wis.'s Community Car, Chicago's I-GO and Austin CarShare are on the scene, too. Their success has attracted the attentions of some well-established veterans in the rental industry. U-Haul, the Phoenix-based truck-rental company, recently launched its own car-sharing program called U Car Share, with 160 PT Cruisers available in 11 cities.

Of course, car-sharing isn't for suburbanites toting kids to soccer practice and commuting long distances to work. Dave Brook, the founder of Car Sharing Portland, co-founder of Flexcar, and author of the blog carsharing.us, found that when kids leave home, parents realize they don't really need two cars anymore. "So when the second car died, they were ready to do car-sharing," he says. "We found that pattern a lot."

But perhaps the biggest car-sharing enthusiasts are people like Dean Ruffner, a self-described "shameless Flexcar fan," who has been a member of the for-profit car-sharing company since last year. Ruffner, 39, works and lives in downtown Seattle. He uses Flexcar primarily on weekends for grocery shopping and estimates that he's saved at least $300 a month by not owning a car. "Every one of my friends complains about driving," he says. "Seattle traffic is terrible. Parking is a huge issue. So that's definitely a touchstone with everyone."

Beyond the logistical issues, another big impetus for the car-sharing movement is the environment. Reduced car ownership means lower fuel consumption and fewer greenhouse-gas emissions. In some areas, cities are supporting car-sharing because they recognize both the environmental and traffic-reduction benefits. "There are certain structural things mostly to do with parking that cities can do to help it along," says Kevin McLaughlin, president of AutoShare, a car-sharing network in Toronto.

In fact, Philadelphia's nonprofit Philly CarShare is the first car-sharing company to partner with a mass transit system. The company, which has about 20,000 members, reimburses those who take the city's mass transportation, the SEPTA rail, to get to one of its cars. Says the company's co-founder and deputy executive director, Clayton Lane: "We're trying to make a societal change whereby people drive less, use public transportation more, bike more and walk more."

Saving them money and reducing stress are just some of the added bonuses.