2009 Porsche 911 Carrera revealed

Porsche's winning 911 formula remains largely unchanged on the outside; it's the inside that counts.

The refreshed 911 Carrera and Carrera S will receive uprated 3.6-litre and 3.8-litre engines with direct fuel injection, and they're finally matched to an optional dual-clutch transmission.

The Carrera's 3.6-litre six produces 15kW more than the superseded engine at 254kW, while the Carrera S is now 282kW (up 22 kW) with potential top speed now just over 300km/h.

The new seven-speed double-clutch gearbox, or Porsche-Doppelkupplung (PDK), replaces the antiquated five-speed Tiptronic automatic and adopts its technology from Porsche's motorsport programs.

The PDK operates in automatic or manual mode using either the gearshift or wheel-mounted paddle shifters. Its 0-100km/h sprint is 0.2-sec quicker than the six-speed manual across the 911 lineup at a claimed 4.5-seconds, or 4.3-seconds with the optional Sports Chrono pack with launch control. It also offers the added benefit of reduced ADR fuel consumption and emissions, claiming 9.8L/100km.

Exterior tweaks include LED daytime running lights and cornering bi-Xenons, new taillamps, and redesigned exhaust tips.

The new 911 goes on sale in Australia on September 20.