Forty-four millimetres doesn’t sound like a lot, but that’s how much wider the new 911 Carrera 4 models are than their two-wheel drive siblings.

The new all-wheel drive 911 is available in four versions; the 911 Carrera 4 and 911 Carrera 4S, and as a Coupé and Cabriolet and although 65kg lighter than its Type 997 predecessor, the all-wheel drive 911 carries a 50kg penalty for its extra girth (1445kg vs 1395kg for the C2S).

Otherwise the all-wheel drive 911s are powered by the same engine and transmission as C2 variants – a 345bhp 3.4-litre flat-six for the Carrera 4 and a 394bhp 3.8-litre flat-six in the Carrera 4S.

The latest version of Porsche’s all-wheel drive system is enhanced by Porsche Traction Management (PTM), an active all-wheel drive system with an electronically variable, map-controlled multi-plate clutch, automatic brake differential (ABD) and anti-slip regulation (ASR).

Torque is distributed between the front and permanently driven rear axles by means of the electronically controlled, fully variable multi-plate clutch, while anti-slip regulation (ASR) additionally reduces spinning of individual wheels by adjusting engine power.

On-board sensors are used to monitor a range of values, including the rotational speed of all four wheels, the lateral and longitudinal acceleration of the car, and the current steering angle. This enables the active all-wheel drive system to respond immediately to a variety of situations, actively distributing torque between the front and rear axles for maximum stability and grip.

A new menu in the instrument cluster informs the driver how the PTM all-wheel drive is currently distributing engine torque between the front and rear axles.

The Carrera 4 will accelerate from 0-62mph in 4.5 seconds (4.7 sec for the Cabriolet) and a top speed of 177 mph (175 mph in the Cabriolet), while for the Carrera 4S the same increment is despatched in 4.1 seconds (4.3 sec for the Cabriolet) with a top speed of 186 mph (184 mph in the Cabriolet).

Economy is said to have improved 16 per cent over its predecessor, with the Carrera 4 capable of 32.8 mpg (203 g/km CO2) with PDK for the Coupé and 32.5 mpg (205 g/km CO2) for the Cabriolet. The more powerful Carrera 4S with PDK achieves 31.0mpg (215 g/km CO2) for the Coupé and 30.7 mpg (217 g/km CO2) for the Cabriolet.

Apart from the wider rear wheel arches, the Carrera 4 features rear tyres which are ten millimetres wider than the Carrera 2 – with 235/40 ZR 19 front and 295/35 ZR 19 rear on the 3.4-litre C4 and 245/35 ZR 20 front and 305/30 ZR 20 rear on the 3.8-litre C4S.

You’ll also notice the illuminated tail-light strip that connects the rear taillights, the dynamically accentuated cooling air intakes at the front end and distinctive side skirts of the all-wheel drive 911.

Porsche 911 Carrera 4S - Type 991The all-new 911 Carrera 4S restores the classic coke-bottle shape and full-width rear lights to the 911.  Did we mention it’s all-wheel drive?

Porsche Dynamic Chassis Control (PDCC) is available as an option on the 911 Carrera 4S, with its active anti-roll system reducing lateral body movement during cornering. It also minimises the lateral instability of the vehicle on uneven ground, through the aid of hydraulic stabilising actuators in the form of cylinders designed to optimise camber.

Lateral roll is counteracted by forces generated at each individual wheel based on steering angle and lateral acceleration, meaning the C4S sits on the road better and can be driver around corners faster and in more relaxed manner.

Porsche Torque Vectoring (PTV) is fitted as standard on the Carrera 4S and as an option on the Carrera 4. PTV works with the manual gearbox, while cars fitted PDK get the electronic Porsche Torque Vectoring Plus (PTV Plus).

They work by applying brake pressure to the rear wheels as required, so that when entering a corner at high speed, moderate brake pressure is applied to the inside rear wheel resulting in a greater amount of drive torque being transferred to the outside rear wheel which supports the steering motion of the car. The end result is improved lateral stability and outstanding traction.

At low and medium speeds, PTV and PTV Plus significantly increase agility and steering precision.

Standard equipment on all Carrera 4 models includes full leather interior, 4.6-inch colour touch-screen Porsche Communication Management with satellite navigation, automatic climate control, Bi-Xenon headlights, a universal audio interface offering MP3 connectivity and a three year warranty.

The Carrera 4 Coupe is priced from £77,924, with the Carrera 4S Coupe retailing at £87,959. The 911 Carrera 4 Cabriolet is priced from £86,583.00, and the Carrera 4S Cabriolet from £96,619.

The new Carrera 4 & 4S will make its first public appearance at next month’s Paris Motor Show, before going on sale in the UK from December 2012.

New across the entire 911 range

The launch of the new 911 Carrera 4 models coincides with several new features available across the 911 model range – Adaptive Cruise Control (ACC), which controls vehicle speed and the distance to traffic ahead and Porsche Active Safe (PAS), which helps prevent front-end collisions – available when ordered with PDK.

In addition, a new sliding glass sunroof is now available as an optional feature for all 911 Coupé models; and driving a 911 with a manual gearbox in combination with the optional Sport Chrono pack now has added responsiveness. In Sport Plus mode, the system automatically double-declutches during downshifts.