This is where the 2009 Porsche 911 Carrera 4 shines. Yes there have been minor exterior and interior upgrades, but all 2009 Carrera models received technological upgrades on their core components; engines, transmissions and the all-wheel-drive system. In addition to the Tiptronic S transmission, the Carrera 4 is also offered with a Porsche dual-clutch transmission with paddle-shifters on the steering wheel.
The new 7-speed PDK dual-clutch is lighter, provides quicker shifts and quicker acceleration than the previous Tiptronic S. The PDK may look like a regular automatic transmission; but it acts and feels more like a 7-speed manual gearbox with its two electro-hydraulically controlled, oil-bathed multiplate clutch packs. One pack controls the odd-numbered gears and reverse while the other controls the even-numbered gears. As one clutch pack engages the gear based on engine weight and speed, the other pack disengages the previous gear. The process results in a seamless and quick shift (60% quicker) when compared to the Tiptronic S. However, like the Tiptronic S, the PDK shifts up and down automatically, though the driver may shift manually via the steering wheel mounted paddles should they so desire.
Source: eGM Cartech