Audi has built a fuel cell hybrid version of its A2 mini hatchback, the A2-H2.

The A2-H2 fuel cell hybrid emits nothing but pure water vapour, yet offers performance similar to a current petrol-powered A2.

A recent competitor in the Challenge Bibendum contest in Shanghai – the world’s biggest competition for sustainable drive and energy concepts – the A2-H2 combines an environmentally sound fuel cell propulsion unit with a high performance storage battery. The PEM fuel cell uses an electrochemical process to convert hydrogen and oxygen into water vapour, an electric current and heat. The electric current is either stored in the air-cooled NiMH traction battery or supplied to the synchronous electric motor, where it is converted into traction energy.

For cruising at moderate speeds the fuel cell normally supplies current to the electric motor alone. When rapid acceleration is required for overtaking, the electric motor takes current from the fuel cell and the traction battery at the same time for maximum power output, making up to 150PS and 425Nm of torque available for brief periods. According to simulation, the A2-H2 is capable of accelerating from rest to 62mph in less than 10 seconds, can reach a top speed of 109mph and can cover up to 137 miles before its three hydrogen storage tanks need refilling with up to 1.8kg of hydrogen. Equivalent to around six litres of petrol, this gives the A2-H2 a consumption figure equivalent to approximately 94mpg.

The all-aluminium body shell reduces weight by over 40 per cent compared to an equivalent steel-bodied counterpart. Combined with a low drag coefficient of just 0.28, this brings benefits in performance and fuel economy.

The latest A2 range has been simplified and now features just two new Special Edition models powered by 1.4-litre petrol and TDI engines with 75PS and featuring extra standard equipment. The A2 1.4 (75PS) Special Edition and A2 1.4 TDI (75PS) Special Edition models are available to order now at OTR prices of £12,715 and £13,695 respectively for first deliveries in January 2005.

No word on when Audi is likely to bring fuel cell technology to the marketplace.