From £24,780
Experimental lightweight prototype highlights future design direction

Our Verdict

Audi A5

The Audi A5 is a classy coupé, hatchback and cabriolet, but are there talents beneath the pretty bodywork?

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7 September 2009

What is it?

Audi’s experimental lightweight version of the A5 coupe. The standard A5 is built around a conventional steel monocoque chassis, but this car is built around an aluminium spaceframe chassis, clad in aluminium panels. The boot and bonnet are made from carbonfibre-reinforced plastics.

Under the skin of the prototype is Audi’s familiar 2.0 TSI turbocharged engine, wound up to 208bhp and driving all four wheels.

Audi says this car points the way forward for the company. Aluminium construction will become more common, allowing future cars to benefit from all-round ‘downsizing’.

This means four-cylinder engines instead of sixes, smaller brakes, wheels and tyres, smaller fuel tanks, better economy and – most important – much-improved ride and handling.

This latter claim is said be a consequence of reducing unsprung weight and, for high-performance models, using lighter, shorter engines that sit further back in the engine bay.

Overall this car is 230kg lighter than a standard-issue A5 3.2 V6 quattro, the performance of which Audi says the lightweight coupe can match despite its power shortfall.

Company engineers say the A5’s aluminium spaceframe construction saves around 110kg over the standard car and the carbonfibre lids save around 50kg. Another 25kg is shaved off by using a four-cylinder engine. The final 45kg comes with ‘hybrid’ brake discs (which are made from gray cast iron, bolted to aluminium centres) and new lightweight wheels.

Audi has also embarked on a general programme of shaving back the weight of all under-skin components, introducing plastic clutch pedals and seats backs as well as detail refinements such as superlight exhausts and even aluminium bolts and screws.

What’s it like?

Autocar had a chance to try the two A5s back to back on a few quick laps of the Bosch test track at Boxberg.

The 3.2-litre A5 (thankfully without S-line suspension) was smooth, torquey, brisk and surprisingly agile on switchbacks, though that was partly thanks to the quattro drivetrain and its positive effect on the A5’s weight distribution.

The lightweight A5 was markedly different. Its weight advantage was starkly obvious, resulting in rather less of a GT feel and more that of a nippy hot hatch. And it did change direction more quickly, losing much of the slight ponderousness that remains in even the new-generation, longitudinally engined Audis.

However, the rougher four-cylinder engine and its gruffer soundtrack were at a marked disadvantage to the sweet V6 unit. Although future A5 buyers will appreciate the car’s newfound fleetness, they could miss the cultured response of a big engine and the luxury overtones that are a consequence of weighty chassis responses.

Audi engineers say they are well aware of this problem and promise the next generation of four-cylinder engines will have to be both much smoother and more aurally upmarket.

Sadly, the smooth Bosch track prevent us from making any definitive statement on the claimed improvement in ride quality, but the dramatic lighter brake discs and wheels will be a huge help on broken UK roads.

Should I buy one?

You can’t. At least not for another few years, until the A5 is replaced as part of Audi’s new aluminium platform strategy.

The big issue for the next A5 will be cost, because aluminium is a more costly material than even the most sophisticated steels, a hurdle that will only partly be offset by mass-manufacturing aluminium platforms.

The company could, though, further offset the extra cost of an aluminium body by dropping V8 engines and most of its V6 units, and fitting cheaper downsized motors.

However, the next-generation four-pot engines will have to be sufficiently smooth and burbling to deliver a premium feel. If Audi’s engineers manage that, the gains in agility, performance and fuel economy delivered by the switch to aluminium could become class leading.

*All performance figures are estimated.

Join the debate

Comments
25

8 September 2009

Has Audi forgotten they made the A2?

If they are going to stick with the north-south configuration could n't they fit a flat six in there? Then maybe make a flat four too? Surely that could be used in a premium branded roadster within the VW group as well.

8 September 2009

[quote Autocar]

Overall this car is 230kg lighter than a standard-issue A5 3.2 V6 quattro, the performance of which Audi says the lightweight coupe can match despite its power shortfall.

Company engineers say that the A5’s aluminium spaceframe construction saves around 110kg over the standard car and the carbonfibre lids save around 50kg. Another 25kg is shaved off by using a four-cylinder engine. The final 45kg comes with ‘hybrid’ brake discs (which are made from gray cast iron, bolted to aluminium centres) and new lightweight wheels. [/quote]

Always good to see manufacturers lightening their cars, but why the pull-the-wool-over-your-eyes comparison with the 3.2? why not just show the 2.0 standard car vs the aluminium 2.0? and why not drop the quattro drivetrain and save another 100kgs immediately?

8 September 2009

[quote Orangewheels]Always good to see manufacturers lightening their cars, but why the pull-the-wool-over-your-eyes comparison with the 3.2? why not just show the 2.0 standard car vs the aluminium 2.0? and why not drop the quattro drivetrain and save another 100kgs immediately?[/quote]

Couldnt have put it better myself.

And if cars are going to get lighter finally why not develope some small V6's so we can keep the smooth delivery, but reduce emissions through cylinder cut off technology etc.

8 September 2009

It's only a prototype. Jaguar are already building their cars out of Aluminum...

8 September 2009

Yeah man, cars need to get lighter!

8 September 2009

"aurally upmarket"... like that ;-)

8 September 2009

It seems to ne that much of this "technology" could be introduced without the aluminium construction - new brake materials, lightweight bonnet and boot lid, seats and so on. Audi should be just getting on with it rather than putting it together with a construction method and material that is prohibitively expensive for this class of car.

8 September 2009

[quote psst]

It seems to ne that much of this "technology" could be introduced without the aluminium construction - new brake materials, lightweight bonnet and boot lid, seats and so on. Audi should be just getting on with it rather than putting it together with a construction method and material that is prohibitively expensive for this class of car.

[/quote]

Thats a fair point. I can understand having these studies, but some of the tech showcased here could so easily be put into production, like you I wish they would just get on and do it.

8 September 2009

[quote psst]

It seems to ne that much of this "technology" could be introduced without the aluminium construction - new brake materials, lightweight bonnet and boot lid, seats and so on. Audi should be just getting on with it rather than putting it together with a construction method and material that is prohibitively expensive for this class of car.

[/quote]

You are missing the point completely - Audi's aim is to make cars as light as possible - and this currently cannot be achieved without aluminium.

Two cases in point:

The new Jag 3.0d XJ weighs less than the 3.0d XF.

The new BMW 5GT weighs a horrendous 2 tons - and Autocar's very recent test confirmed they couldn't get anywhere near BMW's claimed mpg figure.

I say hats off to Audi for showing the way forward - if they can sell aluminium bodied cars at little premium we should all be for it.

8 September 2009

[quote 230SL]Has Audi forgotten they made the A2? [/quote]

Yes, but the A2, A8 and R8 (and Jag XJ, etc.) are comparitively low-production models, and part of the problem with the A2 was that it was too expensive, almost entirely because of the cost of the aluminium structure.

So they are still a way away from large-scale (A3, A4, A5, A6, etc.) production with the aluminium space frame, and that is the key to the serious weight reduction in the next generation of cars, allowing the rest of the car's components to be scaled down accordingly.

Plastic clutch pedals and aluminium nuts & bolts are only going to make minor reductions and won't allow smaller brakes and engine outputs.

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