Manufacturers make big claims about their fuel economy figures. Occasionally, even these claims can be bettered, as Toyota's now closed blog for the iQ managed back in January, extracting 72mpg when Toyota themselves only claimed 65mpg. Often though, real-world driving prevents us from extracting the optimum economy from our cars.Autocar's test then perhaps sheds a little more relevance on achieving high miles to the gallon. Armed with a Ford Fiesta Econetic, a Vauxhall Corsa Ecoflex, an Insight, a Prius, a BMW 116d and a Smart ForTwo CDi, they each hit the track at Bruntingthorpe with a single litre of fuel and a driver trying to achieve as...