A new hydrogen-powered car has been unveiled in London. The RiverSimple Urban Car is powered by a fuel cell which which combines hydrogen with oxygen from the air to release only energy and clean water.The car is smaller, lighter and cheaper to make than conventional hydrogen-powered cars and the makers hope that it will be in commercial production by 2011. The RiverSimple Urban Car is about the size of a Smart car, weighs just 350 kilos and uses a relatively cheap 6 kilowatt fuel cell. 1 kilo of liquid hydrogen is enough fuel to take the car 300 kilometres. Top speed is 80 kilometres per hour and the car can accelerate from 0 to 48 kph in 5.5 seconds. Normally, the problem with hydrogen powered cars is that they are too large, they use a lot of hydrogen which adds to the weight problems, and they therefore need correspondingly powerful fuel-cells which are expensive. But this car needs less of everything, thus avoiding all the classic construction problems of hydrogen- fuelled cars. It also has a neat innovation in the shape of an electric motor for each wheel, resulting in energy savings of 50%. When the car hits the market however, it will not be for sale but will be available for lease at around 200 euros a month.