Porsche has unveiled its latest all-wheel-drive Carrera 4 (C4)  just two months after pulling the covers off its heavily revised 911 Carrera.

The C4 uses a 345bhp 3.6-litre engine while the more powerful C4S has a 385bhp 3.8-litre engine both have the
same direct-injection flat-sixes found in the 911 Carrera.

Unlike previous C4s, Porsche uses an electronic all-wheel-drive system based on its latest Porsche Traction Management (PTM). Compared with its rearwheel- drives, Porsche says this system uses only half a litre more fuel for every 100km clocked in the city.

The usual penalty is around 30 per cent.

The C4 and C4S take 4.6 and 4.3 seconds respectively to hit 100kmh. This is a fraction faster than the two-wheel-drive

Carreras because the extra traction produced by all-wheel-drive more than offsets the additional weight.

Top speeds, however, drop by 5kmh to 295kmh for the C4S, and 282kmh for the C4.

The new all-wheel-drive is a 'realtime' system as the front axle is not coupled permanently. When cruising at a relaxed pace of say, 80kmh, the car is practically rear-wheel-driven. Step on the pedal and up to 20 per cent of torque goes to the front wheels.

If you use the car's impressive Launch Control, the PTM sends 60 per cent of torque to the front wheels to eliminate wheel spin altogether.

On a slippery surface such as ice, the system shifts 100 per cent of torque to any axle to manage the situation.
It does this through an electroactuated multi-plate clutch, instead of the viscous coupling used in previous C4s.

The C4 is available with a seven-speed dual-clutch semi-automatic transmission, which replaces the dated Tiptronic gearbox. But to onlookers, its more obvious attraction is its Turbo-like body.

While the purist may stick to the rear-wheel-drive 911s, there is no denying the C4 has the ability to turn common folk into heroes with its PTM system. By actively varying torque delivery, the system can rescue the car in extreme situations, which can be a bigger boon than swifter take-offs.

Traditional all-wheel-drives tend to understeer, like the first-generation C4s.

The latest rendition, however, feels very much like a rear-driven Carrera. On the track, the car replicates the Carrera's turn-in and neutrality. But it can blast out of an apex sooner and harder.

Beyond that, the car's ride and handling virtues are nearly indistinguishable from the 911 Carreras. So, is better traction enough to win buyers?

Going by past sales figures, the higher cost of the C4 has never deterred buyers.

In fact, it has always matched the 911 Carrera nearly car for car.

To sweeten the deal, the latest range comes with iPod and iPhone interfaces.

Talk about an unfair advantage.