Aluminum is a great material. Light, easy to work, strong if you can design with it right and relatively plentiful (if you’ve got access to lots of electricity to refine it). Audi recently gave a textbook demonstration about just what aluminum can offer by making an A5 prototype that makes extensive use of the alloy.
The A5 in question has allowed Audi to shave nearly 220-pounds from its handsome Coupe. The engineers from Audi swapped out the normal steel bits for advanced aluminum as well as carbon fiber here and there in the interest of fuel economy, emissions reduction and handling agility.
Audi did this as a way to go against the tide of rising car weights. Airbags, door beams and the like have all contributed to cars getting fatter and fatter. Audi took an existing steel-bodied A5 and clearly demonstrated the benefits of the aluminum Audi Space Frame (ASF) concept. The use of ASF reduces the weight of a car body by at least 40% compared with conventional steel construction. That means dropping the overall weight from 3,130 pounds down to 2,888 pounds.
Dropping the weight meant that Audi could do away with the standard V6 and use a four cylinder engine, and still have the same performance. Not only is the performance the same, but naturally, there are gains in economy and emissions and also to other ancillaries such as the brakes and transmission, which can also be reduced in size and weight. The handling is also markedly improved.
So why hasn’t aluminum seen widespread use in the auto industry? There’s a few reasons. First, in comparison to steel, aluminum is a little harder (and therefore expensive) to refine. Aluminum is also more costly to mine in some respects and the tooling needed to work it is also more expensive than the tooling used for steel forming.
There is also the mitigating factor that since gas prices and environmental concerns have only recently come onto the radar of car manufacturers, there has not been the motivation to really make cars all that light. They’ve been used to working with, buying and sourcing steel for the bodies of their cars, so why not go with what you know.
Well, times change, and Audi has pointed out what Colin Chapman and any sportscar guy will be able to tell you: “To go fast, add lightness”.
