The UK-based company Riversimple aims at creating a vehicle that would enable "mobility at zero cost to the planet." They recently presented a prototype dubbed "Rasa" with, according to its developers, zero emissions at tailpipe and c.40gCO2/km Well-to-Wheel – even if the hydrogen comes from natural gas.

If the engineering prototype (designed by Chris Reitz, former design chief for the Fiat 500) is anything to go by, this hydrogen fuel cell (8.5 kW) car will be very light, weighing only 580 kilograms. The carbon fibre monocoque chasis, for example, weighs 40 kilograms, as it's made from lightweight but very strong carbon fibre composites. On each of the four wheels an electric motor is mounted, acting also as brakes. They recover over 50% of kinetic energy when braking. Developers created super-capacitors to store all this energy and provide most of the power for acceleration. 

The two-seater's maximum speed is estimated at a little over 60 mph (96 km/h) with claimed a fuel economy equivalent to 250 mpg (0.9 L/100km) and a range of 300 miles (483 km) on a 3.3 lb (1.5 kg) tank of hydrogen. It will be able to accelerate to 55 mph (89 km/h) in approximately nine seconds.

A public 12-month trial of 20 Rasa prototype vehicles is planned this year with possible launch of a production model sometime in 2018.