Just a few hours before it unveils a suite of hybrids and pure electric concepts at this year's Tokyo motor show, Toyota has revealed that it believes the hydrogen fuel powered machine to be "the nearest thing to an eco-car", and that it is on target to put production models on the market by 2015.

The car that proves these things is the Toyota FCV-R, a Prius-sized concept saloon, powered by a hydrogen fuel cell, which proves that Toyota's productionised hydrogen fuel cell powertrain can now fit a normal car, and does a lot more things besides.

Engineers say they have halved the bulk of the power generation system, compared with 2005 standards, doubled the cruising range to near-normal car levels and found a way to make the system work adequately at any temperature between 30 and 105 degC, when extremes of temperature were previously much more problematic. Durability had improved by a factor of three, as well.

The big problem to be faced between now and 2015 is cost reduction, Toyota says. Present cars would cost at least £80,000, and the company knows this must be reduced.

But the omens are good. According to estimates, Japan already produces enough hydrogen as the biproduct of steelmaking and chemical processes to fuel a fleet of five million cars.

That seems to mean that this small and crowded country, traditionally regarded as fuel-poor, could fuel at least 10 per cent of the cars on its roads from existing sources, provided it can develop foolproof fuel transfer and storage systems.