Audi has produced a prototype aluminium-bodied A5 coupé to demonstrate the virtues of lightweight construction. The project also marks fifteen years since the launch of the A8, Audi's first aluminium car.
Based on a regular
steel-bodied A5, the prototype uses the Audi Space Frame (ASF) with aluminium and carbon fibre-reinforced plastics to reduce the vehicle weight. A conventional A5 tips the scales at 1,420kg but the prototype is only 1,310kg, a weight difference that is like leaving a heavy passenger at home.
The benefits of fighting the fat include better economy, lower emissions and improved road holding. With the 2.0-litre TFSI turbocharged engine in the lightweight body the power-to-weight ratio is 159bhp/tonne, which Audi compares favourably with the 170bhp/tonne of the 3.2-litre, steel-bodied A5. The smaller engine should mean less front-end weight whilst the transmission, suspension and brake components can also be lighter lending credibility to the claims of improved ride and handling.
Not only does saving weight in the body benefit conventional petrol and diesel cars, but Audi describes it as 'an essential prerequisite' for electric vehicles. Along with aluminium the company is experimenting with carbon fibre-reinforced plastics, magnesium and high-strength steels. By saving 100kg, fuel consumption should improve by between two and four miles per gallon, with CO
2 emissions falling by around 8-11g/km. Expect to see weight-saving techniques applied to all future Audis.
John Lambert - 1 Oct 2009
