Didn't your mother teach you how to share? If so, you might already have the key to having some wheels without the aggravation of actually owning a car.

While car sharing services have been around in the U.S. since the late 1990s, they've only lately began to really catch on. Today, Massachusetts-based Zipcar is the world's largest car sharing company, with its 605,000 members in the U.S., Canada and the United Kingdom sharing 9,000 cars.

There are dozens of car sharing programs around the U.S., but Zipcar controls the market and has helped advance to concept of car sharing as a convenient way to drive, save money and be green.

Zipcar's Beginnings

Efforts at car sharing services go back as far as the 1940s in Europe, but the roots of car sharing in America can be traced back to 1998, when Dave Brook, an energy-conservation agent for Oregon State University, started up a car-sharing service in Portland, Ore., with four Dodge Neons. The effort eventually grew to two dozen cars before Brook sold the business to Flexcar, a Seattle startup company, in 2000.

Zipcar, which itself started up in 1999, absorbed Flexcar in 2007. From the start, the company did away with lock boxes and log books that other services used, instead taking the operation online.

In more than 125 cities across the country, including New York, Seattle, Los Angeles and Washington, D.C., Zipcars are parked in small clusters in neighborhood garages.

To reserve a car, you go online, find the nearest location and pick out your car. Honda, Toyota, Mazda, Volkswagen and Volvo are the Zipcar standard-bearers, and the Mini Cooper its signature ride.

To access the car, you wave a "Zipcard" in front of a reader inside the windshield. The program costs $25 to apply and $60 annually, although "extra value plans" are available without the annual fee with a monthly minimum commitment. Hourly rates start at around $7, with daily rates from around $65 -- and that includes gas, insurance and up to 180 miles.

Is It Right For You?

Car sharing isn't for everyone.

According to Susan Shaheen, co-director of the Transportation Sustainability Research Center at the University of California-Berkeley, it generally works better in urban areas and for drivers who drive less than 7,000 to 10,000 miles per year. It's also not ideal for daily commuter trips.

If you like things just so or wouldn't dream of lending your own car to a friend, you might want to reconsider as well. While members agree not to smoke, let their dogs loose or leave fast-food wrappers in the car, there will likely be signs others have used the car.

How Much Savings?

Depending on your driving habits, car sharing might allow you to save some green. Sharing eliminates the fixed costs of private car ownership, which AAA pegs at $8,000 per year for a midsize sedan.

"It causes vehicle owners to reevaluate their vehicle usage and whether or not they need to own a vehicle," Shaheen said.

Zipcar also claims to be an eco-friendly alternative to automobile ownership.

"Each Zipcar put on the road replaces 15 personally owned vehicles," said Steve Bishop, general manager of Zipcar Chicago. "Members give up their private cars, drive less and walk, bike and use public transit more often. It doesn't get much greener than that."

Saving Environment, Changing Culture

But you don't have to sell Champaign, Ill., resident Carol Timms on Zipcar or the idea of car sharing.

Timms, an environmental activist and education consultant, signed up for her membership before the company even expanded to the Champaign-Urbana area. She uses the cars for errands around town and board-meeting trips to Chicago.

"First comes Tonka Trucks then Hot Wheels," she said. "Before you know it, you're dreaming of a GTO, a Shelby Cobra or a Barracuda. Americans are obsessed with our cars."

Timms is an especially big fan of the Toyota Prius, one of several cars Zipcar has in her area. She said the average Zipcar user saves $500 a month versus owning a car.

"I'm an energy geek from way back," she said. "This is great for the environment. It means a lot fewer people will need to buy cars."

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