PSA Chairman Jean-Martin Folz feels that the best way to save on fuel consumption of cars in the short term is by boosting the use of diesel and by adding bio-fuel to diesel. For the medium term, hybrid diesel engines would offer further reduction in consumption and greenhouse gas emissions, while fuel cells, which release energy from the reaction of hydrogen and oxygen with a catalyst, were for a later stage, he said.

“This technology is still at its early stages but offers a real answer for the future,” he said, as PSA unveiled the Genepac fuel cell — an 80 KW power unit the size of a big suitcase that can be used in light municipal vehicles. It can run for 500km (310 miles).

PSA officials said that the cost and size of the fuel cells remained a problem that needed to be solved. Part of the fuel cell is made from platinum, which is an expensive precious metal. At 57 litres, Genepac is much smaller than previous versions but would still not fit in a small passenger car.

Folz remained scathing about petrol hybrid engines, such as developed by Japanese rival Toyota Motor, saying these still consume more than diesel engines. According to the Washington-based Society of Automotive Engineers, a fuel cell can be two or three times more efficient than an internal combustion engine.