A very simple and effective way to increase any vehicle's fuel efficiency, stop-start technology allows the car's computer to shut the engine off when it would otherwise only be idling, such as when waiting at a stop light or in stop-and-go traffic. The engine starts itself right back up when the accelerator is depressed, offering seamless performance while saving all the fuel that would otherwise have been wasted.
But Porsche buyers won't have it, and the company's engineers are at a loss for eeking further improvements from the 911's flat six. The smaller, lighter Boxster might be able to get its CO2 emissions down to 180g/km, reports CAR, but it would be nearly impossible to get the 911 much below 200g/km, with 150g/km being out of the question.
The addition of stop-start technology could shave as much as 10g/km CO2 from the combined-cycle rating of Porsche's cars, however. Such a simple and inexpensive emissions reduction will become increasingly rare and at the same time more important as emissions standards clamp down in the EU and elsewhere. Still, buyers looking for the maximum in outright performance aren't concerned with such matters, and would prefer their cars to be free of the encumbrance.