Panamera sees the light

BY Graeme Fletcher. Apr 17 01:00 am

THE ability to put sports car and fuel economy in the same sentence is difficult at the best of times. In the Panamera, Porsche has accomplished the feat and it all boils down to sweating the details and shaving mass. The latter, pun intended, weighs heavily on fuel economy.

When Porsche designed the Panamera's body, the aim was simple: Make it as light as possible without giving up the required strength. As such, the body is a blend of exotic materials -- aluminum, magnesium and plastic are combined with several different types of steel. Peel the paint layers back and the bulk of the brightwork is aluminum, including the front fenders, doors, hood, liftgate and rear seat frames. This makes up 22 per cent of the total body mass. The radiator support and the window sashes are made of magnesium (2 per cent of the body mass), and there are small plastic inserts in the trunk floor and liftgate (1 per cent).

The rest of the structure (75 per cent of the mass) is steel. The sides of the car, including the rear fenders, are made from regular steel. High-strength, ultra-high-strength and stainless steel round out the balance. As ultra-high-strength and stainless steels are about eight times stronger than regular steel, they cut the overall mass appreciably without giving up rigidity. To say performance and fuel economy would suffer without these advanced steels is an understatement.

The Panamera's 4.8-litre V-8 engine uses direct fuel injection and VarioCam Plus (variable valve timing and valve lift of the intake cam) to deliver the right power, while cutting fuel consumption and exhaust emissions.

While it is derived from the Cayenne's engine, the Panamera's unit uses magnesium, which cuts its mass by 5.4 kilograms. To maximize the fuel savings, the engine is also shut down whenever the car comes to rest -- this idle-stop feature shaves 0.6 litres per 100 kilometres.

The only transmission coming to Canada is the Porsche Doppel-kupplungsgetriebe (PDK). This seven-speed twin-clutch transmission is completely new -- only the two clutch packs are shared with the 911's PDK.

The Panamera's new PDK is not only 15 kilograms lighter than a conventional automatic, good for a consumption reduction of 0.8 L/100 km, its mechanical efficiency shaves another 0.8 L/100 km off the overall consumption. The fact it shifts impeccably regardless of the driver's urgency is a significant side bonus.

The gearbox also feathers its two clutch packs so the first-to-second shift is undetectable. This simple twist allows the use of an abnormally low first gear, which delivers the desired leap off the line without hindering driving comfort or fuel economy. Feathering the clutch packs during all shifts could eventually bring a shift-free gearbox that offers many of the advantages of a CVT without the downsides.

 

-- Canwest News Service