WITH the cone of Mount Fuji as a picture-postcard background, a white 4x4 scoots round a test track 90 miles southwest of Tokyo. It looks like an ordinary vehicle, but there’s one oddity – it has no exhaust pipe.

There is something else out of place. It doesn’t make any noise. At 60mph, there is no engine note, just a slight hum and the odd gurgle, rather like the noise you might get from a gas-fired boiler.

Peek under the car and you get a clue to its secret. An occasional trickle of water drops on to the road, a telltale sign that it is powered not by a conventional engine, or even a newfangled hybrid, but something much more space age – a fuel cell.

Fuel cells make electric power by combining hydrogen with oxygen and harnessing the current that results from the reaction. The exhaust gas is not carbon dioxide, as with a conventional engine, but water or, rather, steam.

Fuel cells have been used in some exotic applications, such as the US space programme, for years, but are in their infancy in cars. Toyota, maker of the vehicle buzzing round the Hiroshi-Fuji test track, doesn’t think they are likely to be commercially available until 2015 at least.

Most other leading carmakers have fuel-cell vehicles under development. What makes Toyota’s version noteworthy is that the Japanese firm has a powerful voice. Not only is it nearly certain to overtake General Motors as the world’s biggest carmaker by the end of the year, but its fast-selling hybrid cars mean it is also winning the race between big manufacturers to go green.

At its research and development centres in Japan, Toyota executives are planning for a future without oil, forecasting that there will be constraints on supply from 2030. If Toyota wants to remain king of the car business, it has to get its bets on environmentally friendly and alternatively fuelled vehicles correct — and its rivals, which are investing heavily in similar and markedly different technologies, will be hoping it makes a false step.

Typically, Toyota already has another trick up its sleeve to follow the success of its best-known hybrid car, the Prius. Thanks to its futuristic styling as well as its green credentials, the dumpy hatchback has become fashionable. It cuts emissions by having both a petrol engine and a battery coupled to an electric motor. The battery powers the car at low speed and in stop-start traffic. At high speeds the ordinary motor takes over.

The Prius has been a big hit in Europe, where Toyota should sell nearly 40,000 this year, with a target of 100,000 by 2010, and 1m worldwide early in the next decade.

“We will double the number of models we have available only as hybrids,” said Katsuaki Watanabe, Toyota’s president, who said it was well advanced in plans to cut the weight and cost of the power unit by half, and who did not rule out launching a separate Prius brand, as the company has done with the luxury Lexus marque.

And the Prius has found an unlikely sets of fans.

“It has become a favourite with taxi drivers in Italy,” said Thierry Dombreval, Toyota’s European boss. “They like it because the big battery means they can use the air conditioning without having the engine on.”

Toyota’s next cunning plan is a “plug-in” version. It has an even larger battery and can run up to 6.2 miles on the power from this alone. Yoshitaka Asakura, head of development for the new car, said that if it is run for an average of 15.5 miles a day and charged up overnight on cheap-tariff electricity, its operating costs will be up to 41% lower than today’s Prius.

Toyota has made the car easy to use. The plug-in point is tucked under a second fuel-filler flap, and it connects with a domestic socket. The battery will take 1.5 hours to charge, said Asakura.

But don’t put your name down for one just yet. Although the plug-in is up and running and will be tested in France next year, Toyota executives say it is unlikely to be on sale much before 2011. It will be offered as an option — a more expensive option — of a new version of the Prius, which is expected on the market in two years.

Toyota’s Japanese and US rivals are forging ahead with similar, and in some cases much more ambitious, technologies. Honda, whose hybrid appeared at the same time as the original Prius but which has not enjoyed the same sales success, used last week’s Tokyo show to outline plans for a cheaper (£14,000) hybrid model to be introduced in 2009, and a hybrid sports coupé.

“This represents a new phase for the hybrid,” said Honda president Takeo Fukui. “After 2010, we expect 10% of Honda’s global sales — about 400,000 cars a year — to be hybrids.”

General Motors, meanwhile, is working on a system called “E-Flex”, which it intends to offer for sale in a small car from 2010. E-Flex is technically a hybrid, but unlike the Toyota and Honda systems its combustion engine (petrol or diesel) does not drive the car directly, but is simply there to keep the battery charged if needed.

GM could come unstuck with its plans to use a smaller, lighter and more powerful type of battery than Toyota’s. E-Flex is based on a lithium-ion cell, similar to those used in mobile phones and laptop computers. Toyota and other hybrid makers use bulkier nickel-hydride batteries. Doubts over the suitability of lithium-ion for cars have been raised by a spate of fires in laptop power units.

Watanabe confirmed that Toyota was working hard on lithium-ion powerpacks, too, but his engineers say they still have doubts. “To withstand automotive use, they need to demonstrate reliability, safety and long life,” said Yoshihiko Masuda, Toyota’s head of research and development.

Nissan believes it has a head start. It has formed a joint venture with the Japanese electronics firm NEC and expects to have hybrids and pure electric cars available in 2010.

“For urban driving I am convinced that electric vehicles are the answer. There is increasing pressure against cars in cities, and the electric car is the only way of achieving zero emissions and zero carbon dioxide — apart from the fuel cell,” said Carlos Ghosn, chief executive of Nissan and Renault.

Ghosn and Watanabe agree that the main obstacle to fuel-cell cars is the availability of refuelling points. Fuel cells run on hydrogen, which is stored on the vehicle in high-pressure tanks.

“In terms of the hardware of the car, we are not far off,” said Watanabe. “But the commercial production of hydrogen and its widespread availability is going to be very difficult.”

Green show

TOYOTA’s Katsuaki Watanabe doesn’t just want his cars to be more environmentally friendly, like the Prius. He also wants them to make the air cleaner when they run, make you healthier when you drive them, and never crash.

And Watanabe says he is sticking to his plans.

‘I am not changing my mind about this. It was a big challenge to our engineers, but they have a way forward now.’

The theme of social responsibility was on show in Tokyo.

Toyota presented the 1/X, a super-lightweight carbon-fibre saloon, and two more extreme concept cars, the comic book RiN and the Hi-CT tall-boy ‘urban truck’.

Honda showed the Puyo, whose neoprene body is soft to the touch and changes colour to match the driver’s mood.

Mazda, Mitsubishi, Suzuki, Subaru and Toyota showed their personal-mobility vehicles — some like motorised bath chairs with tiny electric motors.

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