Alistair Weaver, VP of Editorial and Editor-in-Chief
To change up a gear in the 2009 Porsche 911 Carrera S Cabriolet, you just rotate your right hand clockwise by 20 degrees. Your palm — the fleshy bit below the thumb — connects with a plastic switch and engages the next cog. After 25 years of development, this is the curious way in which Porsche has chosen to debut its new PDK double-clutch gearbox.
The introduction of the PDK system will snaffle the headlines, but it's not the only significant change to the 2009 Porsche 911. Both the Carrera and Carrera S feature an essentially all-new engine that introduces direct injection for reduced fuel consumption and cleaner exhaust emissions. So the evergreen sports car is now greener than ever before.
With a host of other detail changes differentiating the 2009 Porsche 911, the new car will go on sale in Europe on July 5 and reach the U.S. in September, priced from $75,600 for the entry-level Carrera coupe. The 2009 Porsche 911 Carrera S Cabriolet will be priced at $96,800, plus around $3,000 for the PDK gearbox.
Magic Shifter Porsche originally developed a dual-clutch transmission for the 956 Group C racing car of 1983. But while the first PDK worked in competition, it took some time for Porsche to develop the computerized technology required to make the transmission comfortable and reliable enough for everyday use.
In essence, PDK (Porsche double clutch) is like a hydraulically activated manual transmission, only split into two separate units. One clutch serves gears 1, 3, 5, 7 and reverse, while the second clutch operates cogs 2, 4 and 6. When you select a gear, one clutch opens while the other shuts. The net result is a transmission that changes gear 60 percent faster than the old Tiptronic S automatic and weighs 22 pounds less.
In addition to an automatic mode, there are three specialty modes to choose from — Normal, Sport and Sport Plus. The automatic mode really sets a dual-clutch transmission apart from the single-clutch automated manuals we've seen from Aston Martin, BMW, Ferrari and others. Just as with a lowly Volkswagen GTI, the Porsche 911's PDK transmission lets you drive it as thoughtlessly as an automatic, without giving up the performance and fuel economy of a manual transmission. In comparison, single-clutch designs require you to work with the gearbox to get anything approaching smooth progress.
Let Dr. Porsche Shift for You Since there's no torque convertor to get in your way, the PDK takes the slack out of the automatic transmission concept. If you twitch your right toes, the car responds, just as it does with a manual transmission. Our only real criticism regards the PDK's tendency to fidget for gears in a search for optimum efficiency, and also to shift cogs mid-corner.
If you want more control, you move the gearlever across the gate to the manual position. You now have two options. Push and pull the gearlever, or operate the switches on the steering wheel. Neither is very satisfactory, actually. According to August Achleitner, the Porsche engineer with overall responsibility for the new 2009 Porsche 911, the company flirted with the idea of steering-wheel shift paddles, but instead decided to employ a switch system similar to the Tiptronic S automatic since the concept would be familiar and easy to use.
No doubt there's merit in the reasoning, but the end result is an awkward, inelegant solution that's devoid of the tactile sensations that we think are critical to the Porsche brand. The action of the console-mounted shift lever also feels counterintuitive because you push the lever forward to shift up and pull it back to shift down. This feels particularly odd under braking, when your natural momentum is pushing your body forward even as you're trying to pull the lever backwards.
Achleitner admits that it would be relatively simple to develop alternative control systems for the PDK and that shift paddles might be considered for high-performance versions of the new 911, such as the GT3. Let's hope so.
By the Way, an All-New Engine Porsche's engine boffins reckon that every single component in the 911 engine has been either replaced or redesigned. There are 40 percent fewer parts and 11 pounds less. Even the bore and stroke have been slightly altered, as the Carrera engine now displaces 3,614cc and the Carrera S engine displaces 3,800cc. A new electronically regulated oil pump ensures constant oil supply under extreme cornering loads.
Most important, direct injection has come to the 911 engine. It has required a thorough revision to the cylinder head. Cooler combustion chamber temperatures have permitted a dramatically taller compression ratio of 12.5:1, compared to the 11.8:1 compression of the former 3.8-liter engine and the 11.3:1 compression ratio of the 3.6-liter engine.
The results are impressive. The Carrera S engine uses 12.8 percent less fuel than its predecessor (on the European test cycle) and emits 15.2 percent less CO2. Meanwhile, power is up by 8.5 percent to 385 horsepower and the torque climbs 5 percent to 310 pound-feet. Porsche claims the PDK-equipped 911 Carrera S (which is quicker than the car equipped with a conventional manual transmission) will get to 100 km/h (62 mph) in 4.3 seconds and ultimately reach 186 mph.
Ecology Without Compromise This is a remarkable engine. When you're clicked into the PDK's 7th gear, it offers quiet, relaxed cruising, and yet four quick clicks of a switch will send the power plant into hyperdrive. Of course the impressive acceleration time to 60 mph is assisted by a new launch control, but the engine's performance at high speeds is no less impressive. Even above 100 mph on the German autobahns that were part of our test route, the Carrera S surged forward with effortless ease. It makes the current-generation turbocharged engine seem almost superfluous.
Fears that the introduction of direct injection and the drive for eco efficiency would have compromised the Porsche bark can be quickly allayed. This is a horizontally opposed six-cylinder power plant developed by the engineers of Weissach after all. The S engine, quiet and unassuming at low revs, emits a glorious howl as the redline of 7,250 rpm approaches. If anything, this new lean and green engine sounds even better than the old one.
There's a Car Attached We're told that the 2009 Porsche 911 stands out "clearly and convincingly at very first sight." Well, it's true that there are new LED front and rear lights, bi-xenon headlights, revised front air intakes and outside mirrors, new wheels and tweaked tailpipes. Inside, there's a redesigned infotainment system with touchscreen technology.
In sum, these changes add up to not very much. Unless you're a die-hard 911 spotter, the new model is likely to pass you by unnoticed. Not that this will worry Porsche's customer base — they've always enjoyed the evolutionary approach, and function is more important to them than form.
Porsche enthusiasts will also instantly recognize the driving experience. There might be a new engine and gearbox, but the exquisitely precise steering, wonderful body control and die-hard brakes that we associate with the traditional 911 remain present and accounted for. The PDK-equipped car also lets you choose damper settings independently of the gearbox mode. On our route around Stuttgart, the softer damper setting with the most aggressive Sport Plus transmission mode proved the most satisfying.
The cabriolet body style remains impressively stiff in relative terms, but the more rigid coupe will remain the purist's choice. And our particular test car suffered from a disappointingly high level of wind noise at cruising speeds.
Is This Transmission for Us? Porsche admits that it doesn't really know how many people will choose the PDK option. Its conservative estimate is around 50 percent, but one engineer reckons the figure could be closer to 90 percent. (The current Tiptronic S automatic finds its way into about 40 percent of 911 models.)
There's no denying that more enthusiasts will be seduced by the new transmission than the languid old auto. The PDK is marginally faster and even marginally more fuel-efficient (thanks to a tall 7th gear) than the six-speed manual transmission. Yet the choice will still come down to personal preference. There is still joy to be had in the perfect execution of a manual gearchange and — for what it's worth — a Carrera S coupe with a manual transmission would still be our personal choice.
For the majority of drivers, though, PDK will only enhance the appeal of this 2009 Porsche 911 Carrera S Cabriolet and every other 2009 Porsche 911 besides. The Porsche 911 has changed in some important ways, but it remains the default sports car.
Edmunds attended a manufacturer-sponsored event, to which selected members of the press were invited, to facilitate this report.
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