For the very first time, the new Porsche 911 Targa models that go on sale in November will be available exclusively with permanent all-wheel drive. As with their predecessor (Type 996), the most striking feature of both of these elegant sports cars is the large glass roof and opening rear window.

The outward distinguishing feature of the Targa 4 and 4S is a glass roof blending harmoniously with the sports car’s coupe lines and lending it a distinctive personality. A polished, anodized aluminum trim strip running the length of the roof frame emphasizes the elegant profile.

The glass roof is not just a visually appealing highlight, however, but also ensures a light, airy interior. It can be opened in only seven seconds to as much as half a metre, no matter what the road speed, by means of two electric motors. The maximum roof opening area is then 0.45 square metres. The roof panel is constructed of two-ply specially tinted glass, which is 1.9kg lighter than its predecessor. Wind noises are kept to a low level even at high speed by a newly-developed sealing system. A wind deflector minimizes turbulence inside the vehicle, allowing open-roofed driving even when the outside temperature is low. With the roof closed, a semi-translucent black cloth roller sunblind provides shade in hot weather. Both the glass roof and roller blind are operated by a rocker switch on the central console next to the handbrake lever.

The upward-tilting glass tailgate is supported by gas struts which makes it easy to load the luggage area, offering a maximum capacity of 230 litres with rear seats folded. The tailgate can be released either by a switch on the driver’s side door sill or by the remote control button on the key fob. Closing is facilitated by electronic assistance.

The Targa 4 is powered by the familiar 3.6-litre six cylinder, horizontally-opposed engine, delivering 239 kW (325 bhp). It accelerates the car from 0-62mph in 5.3 seconds and reaches a top speed of 174mph. The more powerful S variant features a 3.8-litre engine producing 261 kW (355 bhp). This model sprints to 62mph in 4.9 seconds, and has a top speed of 179mph.

The Porsche VarioCam Plus valve control system deployed by both engines ensures generous pulling power across the rev range. The 3.6-litre Targa 4 develops maximum torque of 370 Newton metres at 4,250rpm. The equivalent for the S version is 400 Newton metres at 4,600rpm. The engine is coupled to a six-speed manual gearbox with short, precise shift strokes. Optionally, customers can choose the proven five-speed Porsche Tiptronic S automatic transmission, allowing very sporty gear changes using the finger switches mounted on the steering-wheel spokes.

The new Targa uses the same bodyshell as the 911 Carrera 4/4S coupe and cabriolet models, and as a consequence is 44 millimetres wider at the rear than two wheel-drive 911 models. Engine power is transmitted to the road by an all-wheel drive system with a Visco multi-plate clutch, which depending on driving conditions applies between five and 40 per cent of the driving power to the front axle at all times. The system thereby ensures well-balanced propulsive power in bends, and improved traction even on wet or slippery road surfaces.

Like all Porsche 911 models from Model Year 2006 production, the Targa also features the Porsche Vehicle Tracking System (VTS) as standard. Designed to comply with Thatcham Category 5 requirements, the highest in the UK, the system features a discreet pocket-sized card, which should be carried when the car is in motion. If the car is moved without the card, or should the car sense itself being lifted or towed, the tracking system is instantly alerted and, using the latest GPS technology, is able to track and locate the car. The Porsche VTS is tailored to fit every car in the Porsche range and is the only system tested and approved by Porsche engineers at our research and development centre in Weissach, Germany. Initial preparation is carried out at the factory with final fitting completed by Porsche Centres.

The 911 Targa 4 and 4S go on sale on November 18 priced from £70,320 and £77,370 respectively, including full leather interior, top tinted windscreen and Porsche Driving Experience programme.