911 Carrera S PDK Cabriolet Tested

Now With PDK - As in Pretty Damn, er ... Kwik

By Angus MacKenzie

Photography by Brian Vance

Trivia alert: Porsche did not invent the dual-clutch transmission. A French engineer, Adolphe Kegresse, who pioneered the half-track vehicle, envisioned the concept in the 1920s and 30s. Porsche did, however, become the first automaker to develop a working dual-clutch tranny, the PDK (Porsche Dopplkupplung), which it fitted to its 962 group C sports racers in 1985 and 86.

That original PDK transmission was heavy and not entirely reliable. But it's still difficult to explain why one of the technology's pioneers has been beaten to the punch by the likes of VW, Mitsubishi, and Nissan when it comes to putting a fast-shifting dual-clutch transmission in a road car. The good news is Porsche's new seven-speed PDK has been worth the wait. It is -- mostly -- sensational.

The PDK helps make the 911 faster. Compared with the regular six speed manual, Porsche claims it knocks two-tenths of a second off the 0-60 mph sprint in Sport mode, and four-tenths of a second in Sport Plus mode. Those claims look solid. Blessed with 30 extra horses -- courtesy of the new DI 3.8L flat six slung out back -- our PDK-equipped Carrera S Cabrio scorched to 60 mph in 3.9 sec., half a second faster than our much-missed, conventional transmissioned 2005 Carrera S Coupelong termer, despite carrying an extra 221 lb (66 lb of which is the PDK tranny). That's deeply impressive: We can't think of another fully crashworthy, mass-produced road car with less than 400 hp that will dip into the threes in the 0-60 sprint.

The PDK also helps make the 911 economical. Official EPA numbers for the 2009 Carrera S Cabrio are 19 mpg city, and 26 mpg highway, an 11 and eight percent improvement, respectively, over the numbers for last year's Tiptronic-equipped S Cab.

The PDK really is an intelligent transmission. Left to its own devices in automatic mode, it quickly figures out how you're driving, and adjusts accordingly. Loaf around town, and the tranny starts shuffling seamlessly between ratios from as little as 1600 rpm: You can find yourself riding in 5th at as little as 28 mph, and 7th at just 48 mph. Out on the highway, that tall top gear means the 3.8L boxer six is turning a lazy 1650 rpm at 60 mph. Switch modes, and the transmission switches moods immediately -- upshifts happen at about 3200 rpm in Sport mode, and a rowdy 6800 rpm in Sport Plus mode, no matter how much you soft-shoe the gas.

Despite huge improvements in suspension and tire technology, driving a 911 quickly is still all about finding the right balance through turns. Here, the PDK transmission comes into its own, its razor-sharp shifts -- particularly in full-commando Sport Plus mode -- minimizing unsettling weight transfers at critical transition points. Even in automatic mode the transmission will not allow upshifts before turns should you lift off the gas, and won't upshift mid-turn until you reach the 7200 rpm redline.

Naturally, the PDK allows Launch Control. The protocol is pretty simple: Select Sport Plus mode; hold your left foot on the brake; mash the gas -- the engine will rev to 6500 rpm and hold; step off the brake. And that's it. We did 10 launch control starts in a row -- our fastest time came on the eighth run -- without a whiff of expensively toasted clutch or unseemly slippage. It feels utterly bulletproof.

So what's not to like about the 911 PDK? Actually, it's the simplest damn thing in the whole set up: the paddle shifters. For some reason Porsche has opted for a system that in manual mode requires you to push the either of the left or right hand spoke-mounted buttons forward to shift up, and back to shift down. It's not only far less intuitive than the more commonly used right hand side for upshifts, and left hand side for downshifts arrangement, but the buttons are more difficult to use than the wand-type levers you find in, say, a Ferrari if the steering wheel is cranked off-center.

For a company as driver focused as Porsche, it's an elemental, almost unforgivable error.

2009 PORSCHE 911 S CABRIOLET
Base price	$96,800
Price as tested	$119,925
Vehicle layout	Rear engine, RWD, 4-pass, 2-door convertible
Engine	3.8L/385-hp/310-lb-ft DOHC 24-valve H-6
Transmission	7-speed dual-clutch automatic
Curb weight (dist, f/r)	3496 lb (38/62%)
Wheelbase	92.5 in
Length x width x height	175.6 x 71.2 x 51.2 in
0-60 mph	3.9 sec
Quarter mile	12.3 sec @ 113.2 mph
Braking, 60-0 mph	102 ft
Lateral acceleration	0.98 g (avg)
MT figure eight	25.0 sec @ 0.76 g (avg)
EPA city/hwy fuel econ	19/26 mpg
CO2 emissions	0.90 lb/mile