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km : Tech


17 March 2011

It’s just 48 hours before the Geneva Motor Show and I’m a bit punchy, having just experienced a whirlwind tour that included the Audi Lightweight Design Center in Neckarsulm followed by a quick trip to Lamborghini headquarters to take in the new and equally impressive lightweight development center where the new Aventador was created. To say there is a lot for my jet-lagged brain to process is an understatement, but luckily the conversation over some hardly lightweight pasta on the shore of Lake Lugano, Switzerland is centered almost exclusively around, of all things, an A5 we’d all just driven back in Germany.

This unassuming A5 is known internally simply as “the Beast”. No normal production car, this sleek coupe is instead a drivetrain mule built prior to last fall’s quattro Concept. Back then its mission was to be a proof-of-concept for the Audi brass to green-light, but even before that it was a lightweight all-aluminum A5 test car with a 2.0-liter turbo. We drove that car in late 2009 and reviewed it on What we didn’t realize then, and honestly didn’t realize until standing on the Geneva show stand a few days after the drive, is that the car is an early prototype for what Audi is calling its “MLB Evo” chassis architecture.

As you may recall, MLB is the modular longitudinal architecture pioneered by Audi-boss-turned-VW-Chairman Martin Winterkorn. Flexible in both size and material, MLB has now been employed for everything from the predominantly steel A4 to the much larger, aluminum-loving A8. And, as the name suggests, MLB is about to evolve.

Using computer modeling, Audi is targeting every point in the car’s architecture and best determining whether to use high-strength steel, aluminum (cast, extruded or otherwise), die-cast magnesium, or carbon-fiber reinforced plastic (CFRP) to optimize the balance of weight and crashworthiness. The savings are significant too. Company engineers boasted that no fewer than 881 pounds will be saved on the MLB-based next-generation Q7.

Audi showed us a bare MLB-Evo chassis in a roughly A4-sized sedan layout, and while it made extensive use of aluminum it looked like no previous Audi Space Frame we’d seen to date. Audi has been busy working on its joining technologies, including things like self-tapping screws, flow drill screws, friction element welding and punch riveting that allow materials such as aluminum, steel or CFRP to be rigidly joined with adhesive layers, thereby eliminating risk of corrosion. As a result, and as you can see from the very few approved photos of the MLB-Evo chassis on display, this means a dizzying and almost patchwork mix of materials. It doesn’t look as artistically sculpted as an A8’s space frame, but it’s actually lighter, likely safer and probably more cost-effective to build in series production. But anyway, back to the A5 prototype.

Along with the advanced chassis, this test mule has a TT RS’s turbocharged 2.5-liter squeezed in with its line of five cylinders pointed toward the front, not the side. It has also been retuned to produce a hair over 400 horsepower, which contributes to the joyful tingle in my hands as they rest on the steering wheel. Additionally, engineers raided the parts bin for lightweight shell-style Recaro seats, along with brakes, suspension, and the full crown gear all-wheel drive system from the RS 5. For the sake of light weight, an S4’s six-speed manual gets to join the fun instead of a seven-cog dual-clutch.

Also changed for fitment reasons was the design of the engine’s intake manifold and airbox. We hear there’s no real performance reason for the manifold redesign, but the 2.5T is taller and longer than even Audi’s V10, so a lower design was necessary in order to fit the engine in both the A5 body and that of the concept car it preceded. No worries, though; the horsepower-per-liter figure for this particular five-banger sits atop the Volkswagen Group chart, above even the Bugatti Veyron Super Sport.

As it sits on the tarmac, “the Beast” weighs in at 3086 pounds, or more than 661 pounds lighter than the RS 5. That’s an impressive lightening, but Audi is aiming to shed yet another 220 pounds from the curb weight should the quattro Concept see the end of an assembly line.

I’m given three laps on a tight test course to feel the difference, and the changes are apparent after just a few hundred feet. This car is in a different league from every front-engine Audi I’ve ever driven, exhibiting absurd levels of neutrality and responsiveness. The turbo motor can’t quite match the RS 5’s low-end eagerness, but still the boost comes on early and the revs skyrocket.

Don’t get me wrong, the car still rolls like an RS 5 and as a larger car, it can’t match the TT RS’s go-kart personality, but this test mule’s grip seems boundless and I almost forget what understeer even means. In a straight line, “the Beast” seems quicker than the more-powerful-but-heavier RS5. Audi claims it will knock out 0-62 mph in “the low four seconds”. For the record, the RS 5 will do it in 4.6.

So why let journalists like us drive “the Beast?” At this point the car has done its job convincing the Audi board to clear the way for the quattro Concept, and hopefully it’s gone further in convincing them to build a production version of that car. With its initial mission complete, it was free to leave Audi’s secret garages to share its abilitities and preach its message of weight loss to us motoring hacks. It also gives a glimpse of a possible production quattro Concept without all the pressure of continuous hooning in a priceless one-off show car. “The Beast” is likely just as priceless, but it also isn’t obligated to duty at auto shows, corporate events and private parties at Villa Piech.

It’s important to note that Audi wasn’t outwardly billing the car as a drivable prototype of MLB-evo, though our intel suggests that’s exactly what it was. Considering that, “the Beast” is also likely a harbinger of a future generation of RS 5 that will be lighter in weight, smaller in displacement, yet even more capable. In that case, we’re ready for the future to arrive.

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