With its Quattro Sport concept, the German carmaker has started to reverse the ‘weight spiral’ – with tangible benefits for driving
IN HIGH-SPEED convoy with a pace car around a secret test track in Germany, the silver Audi looks little different to any other A5 coupé.
The only external giveaways are the bonnet retaining clips and the wide stance. That and the significantly faster lap times being put in. We’re at the wheel of an engineering prototype, one that is tweaked to give an indication as to how a production version of the much-rumoured Audi Quattro Sport concept “might” perform.
That car has yet to be confirmed for the showroom, but this doesn’t matter too much, as the main remit of the prototype is to illustrate how beneficial significant weight loss can be. Despite the unchanged appearance, the car in question was hand-built from aluminium. The bonnet and rear hatch were fashioned from carbon fibre composite and the front seats are lightweight items.
While the prototype employs the suspension and brakes of the high-performance RS 5 model, there’s a turbocharged five-cylinder engine in place of the V8 unit. It produces 402bhp. That may not sound all that impressive next to the RS 5’s 444bhp, but, thanks to a weight reduction of 325kg, the prototype boasts a better power-to-weight ratio.
Straight-line acceleration is not the only advancement. As ably demonstrated by the prototype, agility, direction changes, braking and response all improve.
For years, most car makers have been caught up in what is referred to as a “weight spiral”. Demand for safer cars with lower emissions and more standard equipment has led to an increase in weight. A heavier car in turn needs bigger brakes, a larger fuel tank, larger crash structures and stronger suspension components, which usually all weigh more.
Audi believes it has reversed the trend. An example is made with the recently launched A6 saloon. From 1999 to 2005 this model increased in weight with each new generation. However, the 2011 version is nearly 20 per cent lighter than its predecessor.
Even more significant weight reductions are promised for the next generation of models. The second-generation Audi Q7 SUV is touted to shed 400kg, while the TT range will be up to 120kg lighter across the board.
It’s not easy to visualise weight reductions, but 120kg is about the weight of six medium-sized suitcases, each packed for a week away. Imagine trying to run for a plane with even one of those suitcases in hand. It drains your energy, slows you down and makes you rather slower to change direction. That’s exactly what weight does to a car, regardless of its size or fuel type.
It’s for these reasons that Audi set up its Lightweight Design Centre (ALDC) in Neckarsulm in Germany. About 180 personnel are tasked with developing materials, processes and technology for the next generation of Audis.
While the company outsources the production of many components and sub-assemblies, it is responsible for developing the manufacturing process in-house – and even develops its own alloys.
The ALDC feels more like a small production facility, and it has full car production capabilities to test out new techniques. The benefits of low weight have been explained, but Audi stresses the importance of assessing the suitability of materials – it’s not just about the weight.
Other aspects under consideration include cost of manufacture, servicing and repair, noise and even recycling. More than once, Audi’s engineers wheeled out the “intelligent mix of materials” line, indicating they are not pinning all their hopes on one material.
Audi arguably pioneered the use of aluminium in car bodies with its Audi Space Frame (ASF) in 1994, though even today it’s employed only on the company’s most expensive models. However, the next step is the “multimaterial space frame”, combining components of steel, aluminium, fibre-reinforced plastics and even magnesium in one body.
This approach is already partially taken in the company’s latest models, but Audi plans on doing away with the traditional monocoque construction in all of its cars in the future.
Using different materials together can be tricky though. Joining steel to aluminium requires special techniques and awareness of the propensity for corrosion. This is the sort of challenge the people working in the ALDC specialise in.
Some of the advanced joining techniques were demonstrated, including impressive self-tapping rivets that joined steel, aluminium and fibre-reinforced plastic together in one slick operation.
One of the final parts of the tour shows how high-quality body parts can be produced in carbon fibre reinforced plastic. When asked about the viability for mass production, the engineers shrug their shoulders and admit that it is not ready yet, but that is certainly the intention for the future.
To that end, last year Audi added a new department to the ALDC, called the FRP Technical Centre. Up to 50 people now work in this facility on the development of carbon and other fibre-reinforced plastics. It is these engineers and designers that work closely with their counterparts in (Audi-owned) Lamborghini.
The first fruits of those labours may be something as innocuous as an energy-absorbing structural member made from carbon fibre, or the lightweight carbon fibre roof of the forthcoming Audi S1, but you can be sure that we’ll be driving it very soon. Let’s hope it looks half as good as the Quattro Sport concept.
