A new Audi A5 prototype promises to be more fuel efficient thanks to a 100 kg weight savings. Meet the aluminum Audi A5.

Audi released details about a new version of the A5 that is roughly 100 kilograms lighter than the standard model.  The Audi Aluminum A5 coupe was built substituting the lightweight metal for steel whenever possible.  Carbon fiber was also used to help lighten the load.

Working with aluminum is nothing new for the German manufacturer.  Since 1994, over 550,000 Audi cars have been produced with an aluminum body in the last 15 years alone.  By using the aluminum Audi Space Frame, with "aluminum and carbon fibre-reinforced plastics" mounted to the frame, the prototype was able to use the more economical and fuel efficient 2.0-liter TFSI engine and achieve comparable performance compared to the heavier car with the 3.2-liter V6.

The two versions were available for testing by journalists at an Audi-sponsored event recently, alongside two different versions of the Audi TT.  Performance numbers for the aluminum version of the A5 show a car that has a power-to-weight ratio of about 160 hp per tonne, compared to the heavier, V6 powered A5's ratio of 170 hp per tonne.

Because of the less powerful engine, Audi was also able to use smaller, lighter brakes, and a lightweight transmission.  The company claims the "reduction in unsprung weight" has led to a car capable of changing direction better and faster.

"One of our most enduring aims for the future is to reverse the weight spiral," said Audi board member Michael Dick. The company claims that fuel consumption falls by 0.3 to 0.5 liters per 100 kilometers of travel for every 100 kilograms of weight saved.

"Lightweight design is the foundation of our entire approach to improving efficiency," Dick said.

Gallery: Audi A5 Prototype with Aluminum and Carbon Fiber Construction - Sheds 100kg