Audi is presenting a revolution in the top class at the Detroit Auto Show 2008 – the first 12-cylinder diesel engine in a high-performance roadgoing sports car. The V12 TDI with a displacement of six liters powers a concept car based on the Audi R8. This unit generates a huge 500 bhp and 737.56 lb-ft of torque. Audi is writing a new chapter in diesel technology with this power unit. Equipped with the expertise that Audi has built up through its motor sport activities, the R8 V12 TDI in matt "Grace Silver" embodies superb road handling, pioneering technology and fascinating design.

The V12 TDI is closely related to the engine in the Audi R10, the two-time Le Mans winner – so it catapults the Audi R8 into supercar terrain concerning performance too. It sprints from zero to 60 mph in just 4.2 seconds and its top speed is well over 186.41 mph. The peak torque, reached at only 1,750 rpm, paves the way for effortless acceleration that is unrivaled even at this level.

The Genes of the Winner

Thanks to their high performance and pulling power, all Audi TDI engines are ultra-dynamic sources of power. The brand has often enough demonstrated its sporty character in its production cars, especially the six- and eight-cylinder 3.0 TDI and 4.2 TDI. Audi has also been writing a new chapter in its success story on the racetrack since 2006. The diesel engine in the R10 sports prototype won its very first endurance race at Sebring, Florida, when it was pitted against an entire field of gasoline-engined challengers. But its most crucial victories were surely in 2006 and 2007 in the 24 Hours of Le Mans, when it simply outclassed the international elite.

The V12 TDI race engine in the R10 produces over 650 bhp from a displacement of 5.5 liters, giving it the potential for a top speed as high as 205.05 mph depending on the gear ratios. Its power and sturdiness immediately impressed both fans and experts, who were impressed by its restrained noise level. Unusual for a race engine, this powerful Audi diesel makes barely more than a whisper.

The Drivetrain

Audi's engineers were in an ideal position to use their experience building the racing engine to develop the road version. Like the other power units in this range, the distance between cylinder bore axes on the V12 TDI is 90 mm (3.54 in.). Yet its included angle is 60 degrees, not 90 degrees. This means no free inertial forces or mass moments of inertia can occur with the V12. The results are refined in every respect.

The two turbochargers, which generate up to 2.6 bar of boost pressure, play a crucial role in producing the huge torque of 737.56 lb-ft that the V12 TDI maintains from 1,750 rpm to 3,000 rpm. In developing 500 bhp, the diesel achieves a specific output of 84.3 bhp per liter displacement.

Two large intercoolers reduce the temperature of the compressed air. The V12 has a twin-pipe exhaust system with two particulate filters. The intake system is similar in structure with one air cleaner per cylinder bank, with an airflow meter behind it. Two control units, sharing the workload in a master/slave principle, manage events in the engine.

The Design

The R8 V12 TDI concept with matt "Grace Silver" bodywork looks even wider and more resolute than the core model. It shows its potential through its muscular proportions, accentuated wheel arches and even larger air apertures. The rhombuspattern cover on the air inlets and outlets is the hallmark of Audi's sporty top models and a familiar feature of the current RS generation.

Typical of the side view of the R8 is the sideblade. Much wider in the bottom third, it visually accentuates the engine's position as well as acting as an enlarged air deflector.

The continuous aluminum spoiler lip that connects the front and rear diffusers with side air baffles below the enlarged sills also pays tribute to this version's highly developed dynamic talents.

Ergonomic and Elegant Interior

The interior's design is as sporty and exclusive as the exterior: the characteristic element here is the monoposto – an expansive arc running around the steering wheel and instruments, connecting the driver to the car. The interior consequently picks up on the dynamism of the R8 V12 TDI concept and gives it tactile expression in a form that is accessible the moment you climb in.

The start/stop button for the engine and the Drive Select switch with the Dynamic/Sport/Race settings are arranged on the steering wheel. The latter controls the engine and transmission electronics as well as the magnetic ride dampeners in each of three different modes.

In Race mode, the instrument lighting changes from white to red. The navigation system shows a combined display with lap timer and navigation information for the racetrack being driven. Or supplementary information such as centrifugal force and boost pressure can be called up.

The Audi R8 V12 TDI concept that made such a splash in Detroit has a fraternal twin, and it's headed to Geneva. Finished in Brilliant Red paint and dubbed the R8 TDI Le Mans -- the association with the fabled endurance race carries a lot more weight on the Continent -- the car arrives in Geneva with the same impressive spec sheet as its silver counterpart. A 5.5L V12 TDI is crammed in the space behind the R8's passenger compartment. It packs a bit of a punch, too -- 500 horsepower and enough torque (737 lb-ft) to alter the earth's rotation allow for a 0-62 mph time of just 4.2 seconds and a top speed of 186 mph. That's Euro 6-compliant power, too. Clean and mean -- emphasis on the mean.

Diesel Street Cred: Mean and Green

By John O'Dell, Senior Editor Email
Date posted: 03-16-2008


The adrenal glands are working overtime. We've drawn the ticket that will make us the first person outside of Audi's own development team to drive the awesome 2008 Audi R8 TDI Le Mans Concept. As in, first person in the world.

This is the midengine diesel-powered sports car concept that drew drooling crowds at the 2008 Detroit Auto Show, where it made its international debut as the Audi R8 V12 TDI Concept.

It drew crowds again this month when its name became the Le Mans Concept for the 2008 Geneva Auto Show, where it pretended to be a different diesel sports car with a new coat of red paint covering the hide of matte silver it wore in Motown.

Now that this car has a real name, everyone is hoping that Audi is planning on series production. Company insiders won't deny it, but they're not very encouraging, either. The 6.0-liter, 60-degree V12 diesel is a little longer than the R8's 4.2-liter V8 gasoline engine, and it's still too big for this car's engine bay. This issue is being worked on, but there's also talk of using Audi's 4.2-liter V8 diesel.

Big Tease
Opportunity didn't live up to anticipation, as our first drive turned out to be an epic tease.

This two-seater is a hand-built concept, you see. The only one in the universe, Audi assures us. To protect it there were limits — lots of them.

The drive took place Friday morning on a long-abandoned landing strip, a roughly 500-yard stretch of cracked and pebble-strewn runway in central Florida just on the other side of the racing circuit where the Audi R10 diesel was trying to win the 12 Hours of Sebring.

There were no twisties to challenge the Quattro all-wheel-drive system, no elevations to test the V12 diesel's pulling power. Instead we had just flat concrete that had been a training strip for Boeing B-17 bombers some 62 years ago but now had grass growing up through the cracks.

We couldn't even use the flat straightaway for what the motoring gods would surely have wanted us to attempt. "Please try not to drive at more than 35 or 40 mph," project manager Uwe Haller asked.

Don't Ding It
Haller had spent the foggy, early-morning hours walking the strip and picking up rocks and nails. "Lots of them," he said with a wince. But there were more out there and Heller didn't want speeding wheels to kick up anything that would damage the paint, or the undercarriage, or the polycarbonate (and not street-legal) windshield and see-through roof panels.

For the same reasons, no full-power launches and no spinning tires — no attempts to see if all that torque could overpower the traction control. In fact, all that torque had been dialed back for the inaugural test-drive session to just 443 pound-feet, only 60 percent of the V12 engine's capability.

And by the way, we got the car for a mere 30 minutes, and part of that time was devoured by a forced halt when a vent tube started dribbling diesel fuel into the forward corner of the engine bay (just behind the driver seat) because a safety cap had not been properly installed. Ah, the joys of putting a concept to work!

Better Than Naught
Still, we did get to drive, an opportunity not afforded many. And while we wanted more than Audi was able to give, what we got was a good taste for how impressive this car could be with the shackles unbound.

We settled into the R8 TDI's surprisingly spacious and comfortable cabin at 9 a.m. sharp in front of a small audience of cud-chewing beef cattle while the roar of cars practicing for the Sebring endurance race provided background music.

The car doesn't start with a key, but instead with a double poke of the metallic-red start button mounted on the right-hand spoke of the elliptical, racing-style, flat-bottomed steering wheel with its magnesium rim and leather wrapping. The first poke turns on the electronics, the second starts the engine and a third shuts it all down.

Behind the Wheel
The button is surrounded by a rotating "Drive Select" switch that lets the driver choose from three suspension and engine management modes: Dynamic for everyday driving; Sport for a firmer ride and quicker response; and Race for, well, racing (as much as 186 mph in the right circumstances, Audi promises).

Light off the engine in any mode and your ears are treated to the whirr of the starter, a quick rumble as the cylinders fire and then a subdued diesel clatter as the high-pressure diesel injectors pump away, blasting fuel into the cylinders at up to 26,000 psi.

Hit the gas and the tach hits the 5,000-rpm redline in a blink. Even without flooring it, 1st gear in this car with just 60 percent of the torque available feels like compound low in a Mack truck.

No Room to Run
We got enough speed on a couple of runs — 60 mph before Haller, our co-pilot and official minder, apologetically suggested it was time to back off — to move the six-speed manual through the beefy polished-aluminum shift gates all the way to 4th. Had we been able to paste the pedal to the floor, we could have used up all the pavement with just one upshift.

We also discovered that there's enough torque to launch quite pleasantly in 3rd gear, which would come in handy for those who get tired of stirring a manual on crowded freeways (no dual-clutch automated manual for this diesel, as the torque would overpower the transmission gears).

But back to the drive. There wasn't enough of it to provide a solid feel for the car, but we walked away hoping Audi does launch a production R8 diesel. And with the V12, please.

The brief sampling we got showed us a well-mannered but powerful sports car that does Audi, and diesel, proud.

The Le Mans concept is quite a bit heavier than the standard R8, weighing in at almost 2 tons versus 3,439 pounds for the gasser. The V12 diesel and its plumbing add 220 pounds to the R8's weight, while hefty solid-aluminum side-scoop panels and ground-effects trim that probably wouldn't make it to production anyway add 220 pounds more.

Whassa Matter? No Clatter
Turn on the R8 TDI's engine and you know you've got a diesel back there, but it is amazingly civilized given that after squeezing the V12 into the engine bay, there was no room to provide any acoustic insulation. There's minimal diesel clatter, so the R8 V12 TDI sounds more like a family sedan than a brawny, race-bred sports car.

Haller admits to being a little disappointed. Audi engineers tried unsuccessfully to tune the engine and exhaust for a more muscular note — like the rumbling burble that slides from the pipes of the standard V8-powered R8. "Even the racecar is very quiet," he says. "It's just the character" of the state-of-the-art diesel engine.

That engine is a twin-turbo, intercooled, 5,934cc 60-degree V12, no wider than the gasoline-sucking 4.2.-liter V8 in the standard car but 6.5 inches longer and (more important) almost that much taller. A relatively mild compression ratio (for a diesel) of 16.0:1, a sophisticated fuel-injection strategy to reduce knock and low-friction roller cam followers all help reduce noise. Exhaust plumbing includes particulate filters and 6 gallons of urea to knock down diesel particulate emissions so the car meets the strictest U.S., California and European standards.

Shoehorn Situation
It all makes for a tight fit. Haller's team had to reconfigure the R8's aluminum space frame and add a slight bubble to the engine bay's glass cover to accommodate the big diesel. The major issue is the deep oil sump that's required.

Nobody at Audi will admit that the company is planning to do a production model of the car, V8 or V12, but Haller did acknowledge that engineers are still working on development of a dry-sump oil system for the V12 just in case. This would enable the engine to sit lower in the R8's engine bay, improving its fit and lowering the car's center of gravity.

Right now, the engine is topped by a pair of carbon-fiber ducts that bring cold air to the dual turbochargers via the NACA duct on the car's roof, and it sits so high that it obscures most of the view from the rearview mirror. To compensate, Audi added a rear camera that displays on the R8's in-dash navigation and information screen.

Introspection
Other unique interior touches include a metallic-red tachometer dial, loads of carbon-fiber and polished aluminum trim, well-bolstered racing seats wrapped in black leather with red trim, and woven (!) leather floor mats.

The Le Mans Concept features carbon-ceramic brake rotors with six-piston calipers (monobloc in front and fixed calipers in the rear). At the auto shows the car wore custom 20-inch wheels, but for our drive Audi fitted the conventional R8 19-inch wheels with 235/35ZR19 front and 295/30ZR19 rear Pirelli PZero tires.

To let the driver monitor how well the car is dancing in this footwear, the R8 TDI's dash display also graphically illustrates lateral and fore-and-aft G-forces as the car accelerates, brakes and turns.

Bring It On
The numbers never got impressive during our brief flirtation, but the extra weight should help pin all the potential power of the 2008 Audi R8 TDI to the pavement, allowing it to handle as well at its gasoline-burning sibling.

And despite the weight and impressive power numbers, diesel's inherent efficiency gives the car between 22 and 25 mpg, per Audi's internal estimates — something its gasoline-powered rivals cannot boast.

Looks, performance, fuel efficiency and clean emissions — what's the argument for not bringing it to market?

Leftlane broke the news that Audi would be fitting its R8 supercar with a V10 powerplant earlier this month, but we now have confirmation from Volkswagen's head of powertrain development, Wolfgang Hatz, that the R8 will indeed receive V10 power.

Moreover, Hatz says that the V10 powerplant will not be the one that Audi was reportedly developing specifically for use in the R8. Instead, the R8 will get the same twin-turbo powerplant used in the Audi RS6 Avant. In RS6 Avant guise, the 5.2L engine produces 580 horsepower and 480 lb-ft of torque.

As you may recall, Quattro GmbH director Wener Frowein revealed that the three R8 prototypes that burned to the ground last year were powered by the very same engine. But Hartz told Autocar that the overheating problem was actually solved by using a roof-mounted vent, similar to the one seen on the R8 V12 TDI concept.

It is also being reported that the V10-powered R8 will be dubbed the RS8, which leaves the RS version of the Audi A8 in limbo.

If the twin-turbo R8 has indeed received the green light and this is not just some kind of sick April Fool's Day joke, expect the RS8 to hit the market in mid-2009.