The Vauxhall Ampera will go on sale in 2012, pitched between the Vauxhall Astra and Insignia. Probably, at first, it will be costlier than both — but what remarkable economy it’s capable of. How does 176 mpg grab you, with CO2 emissions of a mere 40 g/km? The best Vauxhall Corsa, by way of comparison, emits 109 g/km. Plus, the Ampera is a full-sized model, with a 300-mile range. It can do 40 miles on electric power alone, meaning most drivers may never see the engine start. More than that, there’s a gasoline-powered “range extender” to take you farther.