One response to climate change and resultant anti-car policy is the emergence of car sharing clubs.

In London such clubs are growing as car owners give up their often barely used cars and opt for paying by the hour or day to hire a car, parked as close as possible to their home or place of work. With congestion charging, parking charges, rising fuel prices and changes to ownership taxes, there are considerable savings to be made compared to owning a car.

Paul McLoughlin, general manager of Zipcar, one of the newest entrants to the European car club market, told just-auto that, for each Zipcar car in London, there are 25 members. In the US, where they are more established, there can be one car for 50 members. Guarantees are made about the availability of cars, such that a new car is added as soon as there is a problem.

Transport for London and the two main London car clubs, Streetcar and Zipcar, have agreed to aim for 180,000 car club members in London by 2011, up from 35,000 to 40,000 today. The Greater London Authority (GLA) is investing GBP5m funding to pay for on-street parking spaces in London boroughs.

But are car clubs a true response to climate change and to they actually cut carbon emissions?  McLoughlin claims that paying for a vehicle by the hour or day changes driving patterns. His members tend to drive on average 1,200 miles a year, whereas before joining up they drove an average of over 5,000 miles, he said.

Research shows that club customers are shunning buying a new vehicle. 50% of members in London's richest borough, the Royal Borough of Kensington and Chelsea, said they would have bought a car if it were not for joining Zipcar. Nearly 20% gave up a car as a result of joining.

Some vehicle manufacturers are naturally concerned that car clubs are a threat to their business. Zipcar has aligned with five brands to supply its vehicles - BMW, Honda, Toyota, Audi and VW. "They were chosen because they have got their act together regarding green technology, and can see that car clubs are complimentary to what they do," said McLoughlin.

The biggest threat from car clubs is to the traditional rental companies, according to McLoughlin. Several say they have started hourly rental schemes but they do not offer the same level of convenience and service as car clubs, which place their cars in specially-marked bays on roads on in car parks across communities. Membership charges are around GBP50 a year with hourly rates starting at GBP3.95 for the smallest cars, and GBP4.95 an hour for medium-sized cars.

Zipcar is the largest car club in the United States and London is its first European location. It has been in the city for just a year, has placed 200 cars on the road and expects to double this by the end of this year. By 2011 it wants 1,200 cars in circulation in the city.

But this is just the start of the firm's European journey. McLoughlin would not say which cities he will target next. It could be more of the UK's biggest cities, or he could move across to other European capitals.

McLoughlin was keen to stress that smaller towns or villages are not being neglected. "Zipcar is a technology company and is keen to license its technology to councils or transport authorities where a car club could replace an inefficient bus service," for example.

The technology consists of a cardkey used to gain access to the vehicle. The ignition keys are kept inside the car. Communications systems track vehicles, tell users' mobile phones when their time is about to expire and/or offer additional time and can also tell staff when there is a problem with the vehicle.

Persuading people to give up their cars is nevertheless a difficult task, even in a city like London where most journeys are by public transport.

"You have to build the right network of cars and customers have to have confidence in the size of the network," said McCloughlin. He believes that Zipcar has a business strategy that differs from other car clubs, particularly because it offers a wider range of cars, many of which are from highly desirable brands.

"We are the 'wholefoods' of the car sharing market."