Audi's R8 has been given a V12 diesel - and enough torque to beat the best. Kevin Hackettreports from Miami, Florida
WHAT YOU'RE looking at here is an Audi R8, but not as we know it. It has a V12 where a V8 normally sits (and some might say it's about time, too) but there are badges on it that are normally found on repmobiles all over Europe. Ladies and gentlemen, say hello to the world's first diesel supercar: the R8 TDi Le Mans Concept.
Only a handful of European journalists have been allowed behind the wheel and now it's my turn, but so far I've been unconvinced for the need to have a diesel supercar. I love the R8 as it is, thanks very much, and was eagerly looking forward to the V10 that will soon be with us. But this . . . this is an oddball.
It's the car that Audi unveiled at the recent Detroit Motor Show, and it was repainted from its original silver to this beautiful red hue in time for Geneva last month. The alloy wheels have been changed to standard 19-inch R8 rims, but otherwise it's as it was for the shows.
Thomas Kräuter, Audi's technical project leader, says: "In October last year I was asked a very simple question: would our V12 TDi engine fit into an R8? After a couple of days we decided that yes, it would and we were told we had three months to get one ready for the show in Detroit."
That was some tall order. The engine bay of the R8 isn't quite roomy enough to accommodate the big (160mm longer) V12 diesel motor, so 70mm of cabin space had to be sacrificed when the firewall was moved forward to make room. Then there was the small issue of cooling to deal with, necessitating bigger air intakes and radiators in the nose, and a sizeable NACA duct in the new glass roof. This pushes cooling air into two carbon fibre channels that lead straight into the V12 (which is already being put to use in the Q7 V12 that will be available for sale by the end of the year).
As I prepare for my drive, a fact that serves to focus the mind more than most is that this is the only one in existence. This means Audi has understandably laid down a few conditions and these exclude tyre-smoking, tail-sliding, rev-limiter hitting hooliganism. Fair enough.
The starting procedure is pretty simple: foot on the clutch and press the red button on the steering wheel. Once you do this the needles on the rev counter and speedometre quickly arc around before coming back to rest - something that takes barely a second. Within this time the heater plugs have done their thing, so you press the red button again and wait for the diesel engine clatter to come.
Only it doesn't come. What you get is a bit of a whirring noise, followed by a bit of a whooshing noise, followed by a gentle mechanical thrashing noise. No taxi rattles, no coarseness, just the sound of 21st century power. If it's all slightly underwhelming, that disappointment is short-lived because the noises, while not classic sports car, are still special. They're just different.
So what's the point of it all? Audi's insistence on championing its lower fuel consumption is a bit weak because if you've got the requisite 100-odd grand to buy an R8, then you can surely afford to put in as much super unleaded as you like. No, the real benefit of an engine like this is torque. Lots and lots of lovely torque, evident from the very first few yards travelled.
To give some perspective, a new Porsche 911 Turbo produces a peak torque output of 620Nm. This Audi puts out 1000Nm, and it's all available from just 1750rpm, turning the R8 into a bona fide battleship. Get to about 30mph and knock it into sixth, then leave it there. When you want to go faster, there's so much power that it gets delivered in an instant hit without the need to change gear. It's impressive enough in this concept car but, as I mentioned earlier, there are limitations in place.
With only a few weeks to get this car from the drawing board and on to the motor show stands, there was insufficient time to develop a transmission strong enough to cope with all this grunt.
So they had to make do with a gearbox from the current A4 (which generates a third of the torque available from this V12 diesel) and a full-bore standing start here could turn that transmission into a pile of swarf within only a few metres.
So the engine has been detuned, and I'm politely asked by Kräuter (who acts as the car's guardian) to not take the car beyond 55mph. He especially doesn't want any hard charging in the first two gears, but once I slot into third I get to push the throttle into the carpet for a precious couple of seconds. The surge is phenomenal and eerie in its near silence - it's savage yet completely civilised. And it's only half what a production version would give. . .
As the speed builds, the noises inside the cabin alter. There are more whooshes as the NACA duct above our heads gobbles up as much cooling air as it can, and there's more mechanical threshing and whistling from the two turbos, but it's all restrained and all good.
It's clean, too. There's a special catalytic converter downstream of the oxidising catalyst and the particulate filter, and under the front lid is an additional tank containing five gallons of an aqueous urea solution known as "AdBlue". Small quantities are injected into the exhaust system, and the hot exhaust gases break the solution down to form ammonia that splits the nitric oxides into nitrogen and water.
Clever stuff, and enough to give the V12 a CO2 emissions output of just 250g/km - a figure normally associated with engines half its size. In fact, the more time I spend with the R8 TDi, the more I warm to it. So it's not as involving to drive as a regular R8, but it's quicker, more civilised, requires fewer stops at the pumps, and is easier on the environment.
If they build it, the diesel R8 will be a 200mph (about 320km/h)supercar for a new generation of buyer. If you're fascinated by technology and enjoy quiet, refined, colossal speed then this could be perfect for you. Pulling up outside Audi's makeshift HQ, I tell my chaperone that I genuinely hope they go ahead and put the R8 TDi into production.
With a glint in his eye and a sly grin, he tellingly replies: "Me too. . . me too."
Factfile Audi R8 Le Mans 'concept'
Engine: 5934cc V12 twin-turbo diesel putting out 500bhp and 1000Nm of torque
Transmission: Six-speed manual, four-wheel drive
Max speed: 300 km/h (estimated)
0-100km/h: 4.2 seconds (estimated)
Fuel economy: 11.3 l/100km (25mpg)
CO2: 250g/km