The purchase by Avis/Budget of Zipcar for a reported $491 million is just the latest big name trying to share a piece of the car sharing pie.
There also are strictly local car-sharing programs, such as AutoLib in Paris, a huge success with 37,000 users, and CarPingo in New York City, which is struggling.
Unlike conventional rentals, sharing can be for as little as 15 minutes, for a quick errand, or as long as a week, and prices include gas and insurance.
Also unlike conventional rentals, users pick up and drop off a vehicle wherever it is convenient, from an on-street spot located by computer, tablet or smartphone. Members have a special code to open and start a vehicle, lock it, and refuel it. Some programs give users a credit on future use if they refuel it.
According to Nick Cole, president of Daimler's car2go program, most users travel one mile or less, and usually can find an available vehicle within a five-minute walk. Car2go also gives users a credit on future use if they leave an electric vehicle plugged in at a dedicated charging station.
Hertz launched its car sharing program, Hertz on Demand, in 2008, and claims to have more than 100,000 members in nine countries. Membership is free to customers already enrolled in the company's Gold Rewards program.
A week after the Avis deal, Zipcar announced it would waive its membership fee in Toronto and Vancouver, Canada, for a pilot program called Access Plan
Hertz on Demand shares gas, diesel and electric cars at rates starting at $6.50 an hour, in cities large cities such as New York and Los Angeles, and also smaller ones including Honolulu, Oklahoma City and Lawrence, Kansas.
BMW launched its car-sharing program, DriveNow, in San Francisco, in 2012, with 70 fully-electric, zero-emission ActiveE coupes. The program includes dedicated parking with re-charging stations.
The BMW car-sharing program began in Germany as a joint venture with the car rental company Sixt, and has 45,000 members in the four cities where it operates, including in Munich, BMW's headquarters. The U.S. program is a solo venture by BMW, which plans to add more cities in 2013.
Mercedes-Benz parent Daimler launched its car2go program in Germany in 2007, using Smart cars. The program has 250,000 members in 17 cities worldwide, half of them in Europe, including Vienna, Amsterdam and London, and plans to expand to Birmingham, England in 2013. The rest are in North America, including Vancouver, Calgary and Toronto in Canada. Car2go added Seattle and Portland in 2012.
CCar2go also is extending the range of EV car-sharing. Stuttgart, Amsterdam and San Diego each have fleets of 300 Smart Fortwo electric drive vehicles. Each city has dedicated parking spaces for car2go vehicles, many equipped with recharging units. These are keyed to operate only with a car2go account, which prevents other EV owners or users to poach the power.
AutoLib in Paris also is exclusively plug-in electric cars.
Electric car sharing is a complicated partnership between the car sharing company, the local government, the local utility and a recharging company. But it's pretty easy for the customer who is green-minded and prefers the EV experience.
Car sharing is on the rise for a variety of reasons. Young consumers--18-25--are under-employed in the U.S. and Europe, and many young people are delaying their purchase of a car for both economic and lifestyle reasons. Also, as car sharing companies make the experience easier and easier, many are discovering them as smart alternatives to both renting and owning.
Car sharing is expected to double by 2016, according to the Rocky Mountain Institute.