Well, basically low-pollution, means low-performance, and we, as drivers, are on the whole not interested in driving cars that are unresponsive and do not accelerate quickly to the speeds at which we like to drive. Fundamentally, the emissions regulations are set too low for the kind of society we have where drivers like nippy cars. Nippy cars sell. One slight aside, manufacturing a car uses about the same amount of energy as driving it for 100,000 miles, if we take into account the cradle-to-grave lifecycling of mining and refining the metals, making the rubber tyres, all the bits of metal and plastic and the countless assembly and delivery processes (that includes non-petrol and hybrid cars too).