Zero-emission vehicle uses four in-wheel electric motors and promises 250mpg and a 300-mile range by Sam Sheehan British carmaker Riversimple has revealed a new hydrogen-powered car that is set to go into production later this year. The two-seat model produces nothing but water from its tailpipe and is capable of an estimated 250mpg and a 300-mile range from just 1.5kg of hydrogen. The Rasa uses an 8.5kW fuel-cell (equivalent to about 11bhp), which combines hydrogen…