Porsche buyers put the brakes on stop-start technology

Published: 23 June 2008

Direct injection and a clever new PDK dual-clutch gearbox have cemented the new 911’s reputation as the greenest performance car around, but Porsche engineers are being hampered from making the iconic sports car even cleaner by the public’s reluctance to accept further green technology

Engineers at the launch of the facelifted 911 told CAR that fitting a BMW-style start-stop system could chop a further 10g/km from the Carrera’s 225g/km CO2 rating but that performance car buyers weren’t keen on having such overtly planet-conscious tech on their cars.

Start-stop works by cutting the engine when the car’s stationary in traffic, and restarting automatically when you touch the pedals to move off again. Every manual transmission-equipped BMW 1-series comes with the technology, excepting the truly high performance versions.

Asked what the CO2 limitations of Porsche’s flat six were, Porsche powertrain expert Thomas Wasserbach told CAR that while “it might be possible to produce a Boxster that emits 180g/km, it would be difficult to engineer a 911 to produce less than 200” and added that “a 150g/km 911 with a flat six is out of the question”.

Future CO2 savings would more likely come from lighter bodyshells and leaner equipment levels, allowing Porsche to maintain performance standards despite engine power outputs actually decreasing.

The seven-speed PDK transmission’s ability to produce markedly better economy and emissions figures than a conventional manual could also spell the end of the stick shifter within five years, according to Wasserbach. Sound outrageous? Not when Porsche expects 80 per cent of buyers to opt for PDK this year, where available. Its 325lb ft torque limit currently makes it unsuitable for the Turbo, GT2 and RS models, but a stronger version is in development.

Would stop-start technology put you off buying a Porsche, or should buyers be embracing such advances, irrespective of a car’s performance? Your comments here please…

By Chris Chilton

Contributing editor, ace driver, wit supplier, mischief maker