She could rent a car to get to work at the northern edge of the city, but that would be expensive. She could take a taxi, but isn't sure she will get one when she finishes work at 3 a.m. And this time, Toronto Transit Commission buses and subways aren't convenient enough for her needs.

Instead, she will walk to a municipal parking lot near her home to pick up a car reserved through her membership in Auto Share, a for-profit Toronto company that offers an alternative to car ownership.

Car sharing offers exclusive use of a car for a fixed period, avoiding the hassles and high up-front costs of owning a car. Its advocates tout it as one way to ease traffic gridlock and promote public transit.

Liz Reynolds, president of Auto Share, says car sharing can extend the reach of public transit, enabling travellers to mix and match modes of transportation.

"We want you to drive a car less, not more," she said.

But some transit officials are skeptical.

Last October, Ms. Reynolds approached the TTC to work with her year-old company to promote car sharing, partly by providing free advertising on the TTC for Auto Share. Over the objections of chairman Howard Moscoe, who was sympathetic to the idea of car sharing, the TTC rejected Ms. Reynold's overture.

"I know they don't get it," Ms. Reynolds said. "They think we are way too small, a weirdo community group." Unbowed, she says she hopes to demonstrate that her members, occasional car users, are the very riders the TTC says it wants to attract in off-peak hours.

TTC chief general manager Rick Ducharme is one of the skeptics. "I'm not sure this is positive or negative" yet, he said. "We have people on the TTC who don't have a car. Are they [now] going to say, 'Why use the TTC?' "

Mr. Ducharme says he is open to being persuaded about car sharing, given its apparent success in Europe. "Tell me the city where it works well and why," he says, noting the need for different modes of transportation to collaborate to reduce car use.

The mix-and-match approach works for Toronto resident Kate Chung.

Every week, she travels to Oshawa to pick up her granddaughter Tahne for an overnight stay in Toronto. Ms. Chung recently sold her car, and a trip to Oshawa would work by public transit only if she travels on GO Transit at rush hour.

As a member of Auto Share, Ms. Chung has more options. From her east Toronto home, she takes the TTC subway to the Broadview stop, walks a few steps to a nearby municipal parking lot, picks up car keys from a locked box and drives off in her Auto Share car.

During the five hours she has the car, she runs some errands, picks up her granddaughter and then returns the car to the parking lot.

"It's silly for people to own when they could share," Ms. Chung says. "Just look what we are doing to Mother Earth."

With Auto Share, Ms. Chung pays a refundable membership fee of $500, a $10 key deposit and a monthly administration fee of $5 to $40 depending on how much she drives that month. In addition to the initial fees, she pays 20 to 40 cents a kilometre for every trip she takes, also depending on volume. Unlike a car rental firm, Auto Share pays for insurance, parking and gas.

Ms. Chung belongs to Auto Share for environmental reasons because she is worried about air pollution. But Ms. Dougherty was motivated to join a year ago for economic reasons.

"It's certainly cheaper than renting a car," says Ms. Dougherty, who finds living in the city expen sive. Having recently purchased a downtown condominium, she had ruled out ever owning a car.

But with car sharing, she says, "Now I can have it all."

Car sharing, introduced in Canada in 1994 in Quebec City, now has an estimated 1,200 users in six Canadian cities. Proponents say the concept is ideally suited to people who drive 10,000-15,000 kilometres a year and only occasionally need a vehicle.

Worldwide, there are an estimated 90,000 car-share members, about half of them in Europe. In Switzerland, for example, more than 20,000 people share 1,000 cars at 600 locations near public-transit stations.

The trend is gathering steam in the United States. Last September, the Bay Area Rapid Transit District in Oakland, Calif., announced a car-sharing pilot project with Hertz Car Rental. For a monthly fee, commuters can reserve cars at selected BART transit stations. Some suburban commuters use the car for the first leg of their trip to work downtown; downtown residents can use it as the final leg to their job in the suburbs.

In Seattle, the city recently teamed up with its regional transit authority in King County to offer car sharing, with an estimated 100 cars expected for the program in its first year of operation.

In Toronto, Auto Share has 14 cars located near selected TTC stations and expects to add another 20 next year.

Despite the cool reception at the TTC, Ms. Reynolds sees opportunities for car sharing at work and in the suburbs, with public transit as a vital link in the chain.

"There has to be an incentive to use public transit," she says. "What we do is provide the backup: When transit doesn't work, you can use car sharing."