However genuine alternatives to the petrol-powered car were eclipsed by a model that aims to cut fuel consumption -- a sign of the times as consumers around the world suffer from record oil prices.

French auto maker Peugeot Citroen chief stole the show with a model equipped with an engine cutout that claims to reduce fuel consumption and carbon dioxide (CO2) pollution by up to 15 percent.

The Stop and Start device, installed in a Citroen C3 petrol-powered compact car, automatically stops the engine when the vehicle is waiting at a red light or is stuck in a traffic jam, for example.

Costing an additional 550 euros (660 dollars), it saves 10 percent of typical fuel consumption in city driving, between six and 10 percent in combined urban and highway use, and 15 percent in blocked traffic, Peugeot Citroen says.

Carbon dioxide emissions, a principal factor in global warming, are reduced by a similar percentage by the system, developed jointly with the French auto components supplier Valeo, the company says.

French President Jacques Chirac expressed particular interest in the system which is due to be installed in 50,000 cars by 2006, when he visited the show in Paris on Friday.

A similar device is included in so-called hybrid vehicles that combine electric motors with petrol engines, such as the Toyota Prius and Honda Insight, and it also features in a Volkswagen compact, the Lupo.

The family-sized Prius boasts one of the world's lowest pollution rates, but carries a premium price, costing around 25,000 euros in Western Europe.

Peugeot Citroen also unveiled a C3 model that runs on natural gas, developed jointly with the state-owned supplier Gaz de France and set for launch in 2005.

Fitted with a gas bottle in the trunk, the vehicle can run for 250 to 300 kilometres (150 to 180 miles) between refills, which are carried out using a pump installed at the owner's home.

"This model answers both the financial and environmental concerns of different types of customer. Natural gas reduces CO2 emissions by about 20 percent compared to petrol and cuts out emissions of lead and sulfur oxides," said Jean-Pierre Piollat, commercial director of GDF.

But the concept of electric cars as an alternative to petrol appeared to be losing ground -- although France's Ecology Minister Serge Lepeltier drove to the motor show at the wheel of a Cleanova, an electric vehicle developed jointly by French engineering group Dassault and car maker Heuliez.

The French car maker Renault has said it may yet build an electric vehicle, in association with the French conglomerate Bollore.

But Renault chief executive Louis Schweitzer said that although the electric car had a "real future" in the city, it was better suited for postal delivery or other local services than for the average consumer.

Looking further ahead, Peugeot Citroen unveiled a fuel cell prototype called the Quark, a zero emissions two-seater model closer in concept to a quad motorcycle than a car.

With an aluminium chassis, the ultralight Quark weighs just 425 kilograms (935 pounds) and can reach speeds of up to 110 kilometres per hour, with a range of 100 kilometres.

Nissan also offered an updated version of its showcase X-Trail FCV model, a fuel cell vehicle with a range of 350 kilometres, as part of a joint program with its French owner Renault to develop alternative energy sources.

Fuel-cell cars are powered by electricity generated from oxygen and pressurized hydrogen gas, but high production costs and a lack of infrastructure for pumping hydrogen are seen as still hurdles to clear before they can reach ordinary car buyers.

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