"In 1991, the Rocky Mountain Institute in the United States published a design for a Hypercar which, it claimed, could save at least 70-80 per cent of the fuel other models used. The Institute's critical innovations involved massive reductions in the vehicle's weight and drag. It proposed that the steel body should be replaced with carbon fibre composites, Kevlar or fibreglass and that the underside of the car be made as smooth as its roof. Then, like the Toyota Prius, it would use a 'hybrid-electric drive' (powered by a combination of liquid fuel and an electric motor) which could turn the energy now lost when the car brakes into electricity. Fifteen years later, though the Institute's design seems to be viable, safe and cheap, and some of its features have been incorporated into real models like the Prius, nothing resembling the whole package has been launched as a mass-market car on either side of the Atlantic. The manufacturers will produce the odd demonstration model - largely, it seems, to keep the regulators off their backs - but while they make most of their money on sports utility vehicles, they are simply not interested in serious fuel economies. It is beginning to look like the last days of the Roman empire." - 'Heat', George Monbiot.