Porsche 911 C4 and C4S 2008 review

The gains in fuel economy, performance, reduced weight and emissions are palpable.

Yet, as far as exterior giveaways go, the updated 997 Series coupes and cabriolets remain discreet.

Just like the Carrera 2 cars which led into the latest update of the 911, the new 4 and 4S, pick up direct injection flat-six engines and Porsche's seven-speed double-clutch gearbox.

The big difference is an electronic four-wheel-drive system that replaces the viscous coupling arrangement that has been used on the 911 for almost 20 years.

The Carrera 4's new all-wheel-drive system is capable of shuffling torque by up to 100 per cent to either the front or the rear axles if needed where the previous system had limited maximum torque split of between 10 to 40 per cent.

Prices and final specifications are yet to be finalised because of the ongoing confusion on the Luxury Car Tax increase, but the new coupes will be in the $220,000-$230,000 range for the C4 and $250,000-$260,000 for the C4S. The ragtop versions are $240,000-$250,000 for the C4 cabriolet and $270,000-$280,000 for the C4S.

All will be on sale from October 25, just over a month after the two-wheel-drive versions reach the showrooms.

On the outside, Porsche fans daytime running lights at the front, the neat LED rear taillight treatment and a reflector strip on the leading edge of the engine bay lid.

Inside, the C4 and C4S offer generational gains with 8.5 per cent more power and use up to 12.9 per cent less fuel while the carbon emissions are lowered by 15.4 per cent.

The C4 coupe lifts from 239kW to 254kW yet reduces economy from 11.6litres/100km to 10.1litres/100km with torque rising 20Nm to 390Nm Gains for the 3.8litre C4S are 283kW (up from 261kW) and a reduction in fuel use from 11.9litres/100km to 10.5litres/100km with torque jumping 20Nm to 420Nm.

On the PDK gearbox front, Porsche is already hinting it may review what it does for the all-new 998 (unofficial code) model which could be out by late 2010 and which could have proper paddle shifters.

The argument against all-wheel-drive layouts continuing to have relevance because of their weight impost hurting fuel economy and performance doesn't ring true in the case of the Carrera 4. Despite weighing 55kg more than a C2, a C4 has lapped Nurburgring's Nordschleife circuit two seconds quicker than its two-wheel-drive equivalent by turning an impressive 7mins 56sec. DRIVING:

Changes to what is unofficially called the 997.5 mean this version of the 911 drives with a little more steering feel and less cornering push.

On the design front, it's difficult for some to pick the updated Carrera 4 and 4S over the 997 series, but behind the wheel the updated all-wheel-drive 911 coupe and cabriolets are a clear and decisive step forward.

On a 170km road drive in the Lowenberger region just outside Berlin, the C4 and C4S were put through a variety of smooth top roads, patchwork bitumen, lumpy and bumpy surfaces and narrow cobblestone lanes.

In retrospect it was a brave move. They were not roads that suited the Active Damping set up where ride height is lowered by 20mm in conjunction with the Porsche Active Suspension Management feature.

Yet the ride on the super-low-profile 19-inch rubber on the launch cars was not surprisingly jarring. Although at times there was a tendency to pick up every little imperfection and corrugation on the road.

The real story is considerable steps ahead in driving dynamics and efficiency.

More weight to the steering and the dialing out of some push through corners, together with a brilliant new electronic all-wheel-drive system, gives the new C4 and C4S a sharper edge.

There is a triple treat waiting for those interested in the upgraded cars with direct injection and the smart PDK transmission in partnership with the electronic AWD combining to give the C4 and C4S coupes and cabriolets even greater precision and surety.

At last a 911 driver can enjoy a truly masterful transmission that finally does justice to one of the sweetest chassis in the business.

Pleasing levels of refinement in low speed shuffling around car spaces and rolling away from standstill have been dialed into the new double-clutch PDK. It actually creeps forward from a stop without any throttle and, while there is a bit of grumbling detected here and there when trawling the car park, the PDK is the best example yet of these wet/dry clutch systems.

In the Carrera 4 coupe sampled on this drive, the PDK unit had few faults although at times the palms of your hands accidentally pushed the button on the wheel to upshift — particularly if any reasonable amount of steering lock was wound on. It's awkwardly placed and accidentally plucking an upshift is not desirable.

With the optional SportChrono system ($2200) you get wildly aggressive shifts when you apply the SportPlus button. The change down from third to second is particularly angry with a short, sharp blip that sends the 3.6-litre boxer engine's into a playful yelp.

Even in drive mode the gear selector readout on the Instrument Panel lets you know what gear you are in and the centrally-located taco with digital speed readout strikes a happy combination.

It's not until you can legally open the taps that you comprehend what all the fuss is about when driving a 911.

A comprehensive drive at a former Russian airfield that saw serious service before the Berlin wall came down in 1989 was an environment made to order for one of the world's most definitive sports cars. The exercises which the C4 and C4S 911s were put through ranged from slalom skidpan runs to long and short handling tracks using ideal lines at maximum throttle and a top-speed blast down a runway.

On the slalom the C4 was driven both the stability systems functioning and turned off and the behaviour was, even for an all-wheel-drive layout, worlds apart.

The new electronic all-wheel-drive set-up and the lockable limited slip rear differential (22 per cent lockable under power and 27 per cent in overrun) give the C4 tremendous confidence when pushed to the edge.

This 911, with its rear-end spread a further 44mm wider than the outgoing model, is so adaptable and balanced that the driver can entice it to behave any way they desire through a corner.

Acceleration times with the arrival of PDK have leaped ahead with 0-100km/h achieved in the C4 in 4.8sec, 0.8s quicker than the Tiptronic S transmissionm and 4.5s in the C4S, a similar gain over the previous model. When the optional launch control is applied that cuts the time further to 4.3s.

The optional Ceramic Composite Brakes (approx $20,000), 350mm in diameter 20mm more than the standard package are monstrous in performance. After flying down a V-max run, and clocking close to a tick under 260km/h, you can punish the brake pedal as hard as you can muster and the car will pull up without any theatrics.