Porsche, like every other automaker under the sun, is under pressure to produce vehicles with improved fuel efficiency that emits less CO2. The current 911 puts out 225 g/km of CO2, but Porsche believes that it can hack another 10 g/km off that figure with the implementation of start-stop technology on its flat-six engines. Not so fast, say Porschephiles. According to the automaker, buyers aren't fond of such a feature on their arse-engined performance machines. Porsche didn't cite the reasons behind consumer's reluctance, but a 10 g/km reduction doesn't seem like much in the overall product scheme of Porsche.