The world of German cars has been surprisingly tame for too long. Sure, you can still buy brutally quick German cars, but the cars of today don’t quite have the tinge of crazy that they used to. Almost two decades ago, Audi used to be so insane that it made the world’s first and only V12 diesel car engine. The Audi Q7 V12 TDI featured a diesel engine so ridiculous it made more power than an American diesel pickup truck and rocketed Audi’s SUV to 60 mph as quickly as a lightweight sports car. It was one of the most ridiculous engines ever put into a modern car by a wide margin.
The Volkswagen Group of the 2000s was perhaps one of the wildest assemblages of automakers in modern history. At the helm as chairman of the group was none other than the infamous Ferdinand Piëch, the man who helped turnthe Volkswagen Group into an engineering powerhouse. Piëch saved Volkswagen from the brink in the 1990s and oversaw the collection of luxury brands like Bentley, Bugatti, and Lamborghini while also shooting VW AG’s other brands upmarket.
The Piëch era also saw the Group’s arguably most insane engineering projects, from the legendary W-engine to the Bugatti Veyron 16.4. Piëch’s madness helped lead to the creation of some of VW’s most infamous vehicles including the Phaeton and the Passat W8. Piëch’s resume includes some incredible hits including the Audi Quattro and some interesting ones like his push for the adoption of dual-clutch transmissions.
But Piëch didn’t just limit himself to creating fabulously expensive hypercars and the occasional oddball Volkswagen. He was also a bit of a diesel nut. Piëch’s engineering prowess helped lead to the OM617 five-cylinder diesel for Mercedes-Benz and he was also instrumental in diesel developments over at Volkswagen AG. Over in Europe, diesel engines spent the 1990s and 2000s rising in popularity to become the default car engine in the region. Volkswagen was right there churning out surprisingly competent and long-lasting engines.
Most of those engines aren’t much to write about, but Piëch’s apparent addiction to overcomplicated engineering led to the creation of the craziest diesel engines ever put into mass-produced vehicles. If you’re a diesel enthusiast in America, you almost certainly know of the V10 TDI that powers the Touareg SUV sitting in my garage right now. The magic of the V10 TDI was that it was a relatively compact engine that produced the kind of power you got from a large diesel pickup truck but packaged it into a mid-sized SUV. But that wasn’t enough, because the V10 TDI was also shockingly quick and sounded like a Lamborghini ate a bucket of bolts.
Without Piëch and some of the coolest engineers to ever grace Audi, the world might not have ever gotten to witness an engine even more mind-boggling than the V10 TDI. The glorious V12 diesel engine powering flagship Q7 SUVs in the late 2000s was inspired by the V12 housed in the field-dominating R10 TDI prototype racer. This engine put diesel trucks to the same and could even outrun some sports cars. Yet, it wasn’t meant to be.
When A Diesel Dominated Racing
As Racecar Engineering wrote in 2008, diesels weren’t exactly a new thing in racing, but what Audi did hadn’t ever been seen before. One of the earliest instances of diesel in racing was the time when Cummins fielded a diesel racer in the 1931 Indianapolis 500 to prove that a diesel could race 500 miles on a single tank of fuel. The #8 Cummins Special became the first car in Indy 500 history to run the entire race without stopping and it even managed to place 13th out of a field of 33. In 1952, Cummins took a diesel-powered racer to what was then the fastest one-lap time and four-lap time in Indy 500 history. Cummins was also known for setting speed records with diesels back then.
In 1987, Cummins then sponsored a race-winning car with Al Unser behind the wheel, though it was not a diesel. Racecar Engineering notes that there are plenty of instances of diesels racing and even winning like the aforementioned Cummins efforts. However, the publication notes, that nobody had gone as far as to build a clean-sheet design for a racing-specific diesel engine. In other cases, a manufacturer adapted some sort of existing engine for racing.
(Correction: The original version of this story said a Cummins-sponsored car won the 1987 Indy 500. That car had a gasoline engine, not a diesel. We regret the error.)
According to Racecar Engineering, the genesis for Audi’s V12 TDI came in 2002. Back then, Audio Sport’s engine technology chief, Ulrich Baretzky, and his engineering team were having meetings with the Automobile Club de l’Ouest (ACO), the organizer behind the 24 Hours of Le Mans. Audi’s team chatted with ACO reps Daniel Poissenot and Daniel Perdrix over dinner, where they talked about the future of racing. At some point, Baretsky mentioned to the head of engine development at Audi, Wolfgang Hatz, that they should build a diesel racer.
As crazy as it sounded, there was a lot of promise in diesel power in racing. Diesel was rising in popularity in Europe and was at that point in half of the new cars sold in the region. At the same time, Audi wanted to prove to Americans that diesel cars weren’t the smoky and slow boat anchors that they experienced back in the 1970s. The idea here was that if Audi launched diesel cars in America and could point to a successful racing effort, maybe Americans would latch on.
Allowing diesels to compete was thought of a good thing for the ACO, too. At the time, diesel was thought to be the green fuel of the future, and the organization was concerned with having a cleaner image for racing. In 2003 for the 2004 racing year, ACO published new rules that, on paper, would have given diesels an advantage in the field. The ACO knew that nobody had a diesel racing engine out there and perhaps the theoretical advantage might spur development.
Per Racecar Engineering, Taurus Lola-Caterpillar entered a diesel racer into racing in 2004, but that car turned out to be a disaster. The racer had a road-going diesel engine tuned for racing, and it smoked so badly and was so unreliable it only lasted 35 laps at Le Mans. Audi learned a few lessons from that failed effort; the first was that using an existing engine wasn’t going to work. Another was that the Lola-Caterpillar car’s terribleness threatened to tarnish the reputation of diesel power. Audi wanted to prove that diesels weren’t terrible anymore.
So the engineers at Audi Sport knew the path forward was to build an entirely new engine. But this was, according to Audi Sport’s Dr Wolfgang Ullrich, “the biggest challenge ever handed to Audi Sport.” The engineers had no prior diesel race-engine projects to learn from, and they didn’t even have a production diesel engine to build off of. The new engine would have to be designed entirely from scratch.
That race where the Lola-Caterpillar failed was where the Audi Sport project really got some legs. At the race, Audi Sport pitched the diesel racer idea to Piëch, where they were given the green light. Now it was real.
While Baretzky’s team didn’t have any diesel engine they could use for inspiration, they did have a gas engine that worked as a good benchmark. The Audi R8 LMP racer (above) featured a 3.6-liter twin-turbo V8 that pumped out 610 HP. As Racecar Engineering notes, this engine was a big deal because not only was it powerful, but it was the only engine that combined turbocharging and direct injection. So, the R8 engine wasn’t just Audi Sport’s benchmark, but also the benchmark for other builders.
Reportedly, the team at Audi Sport laid down their expectations for the R10 engine’s bore, cylinder count, stroke, and external dimensions by early 2004 because these factors impacted the rest of development. Baretzky noted that if you were going to make a mistake with one of the metrics above, you had to do it early, or else you could have derailed development. So all of that was set right at the beginning.
Audi first made a single-cylinder mule borrowing some ideas from the R8 racer’s gas engine. But later, the team would find their engine’s final form, a 5.5-liter dry-sumped 90-degree V12 with four cams and four valves per cylinder. Racecar Engineering continues:
There are two Garrett turbochargers with maximum boost and restrictors as per regulations, as well as air-to-liquid intercoolers. It is the first ever Audi diesel with an aluminium engine block, and although it is probably about 50 per cent heavier than the R8’s V8, there are links with the earlier unit. ‘Apart from the combustion process,’ says Baretzky, ‘we tried to take over as much as we could, because we don’t have to reinvent the wheel every time. There are differences of course because of the demands of diesel, but look at the structure of this engine and you’ll see it is very similar to the structure of the R8. Most of the similarities are in the bottom end, while most of the differences are in the top end. For example, the oil system is adopted from the R8. We’d proved it worked so why do something new?’
The all-important fuelling regime uses Bosch common rail injection with multiple orifice nozzles and Piezo injection valves. Management is Motronic MS14, and the system was a completely new design. As Baretzky explains: ‘we really started from zero to make a system for diesel, and to fulfil the demands of racing. Those are demands you find nowhere else, and although Bosch has been making electronic management systems for petrol engines for 25 years, to make a system for a diesel race engine was a big challenge for both Bosch and ourselves.’
Injection pressures of around 2000bar are far greater even than the 1600bar now seen in production, with combustion pressures way above anything previously seen in any Audi engine. ‘Of course you have much, much higher combustion pressure compared to a petrol engine and that affects the stress on the piston heads, conrods, crankshaft and many other things. You try to make everything as light as possible, just as you would with any other engine, but the loads are there and there’s no use trying to deny it. You have to make it as close as possible to minimum weight while respecting the stresses’.
The resulting R10 TDI engine was so powerful that it overwhelmed Audi Sport’s F1-engine dyno. So that needed a new transmission to handle all of the power. The development team compared their journey to that of America’s Apollo space program, where engineers were faced with doing something that hadn’t been done before, but they made it happen, anyway. The crazy part about the R10 TDI’s development was just how quick it was. The engine was announced to the public in December 2005 and the Audi R10 racer went on to win the 2006 24 Hours of Le Mans just 200 days later.
The car won again in 2007, setting a top speed record of 218 mph while it did it. Amazingly, the wicked-fast R10 TDI won again in 2008, too. The racer also racked up other wins outside of Le Mans.
The World’s Only Production V12 Diesel Car
In 2006 after the R10 TDI’s first Le Mans win, Audi realized it did goof up in some way. Part of the idea behind the racing program was to advertise that Audi was putting racing technology into its road cars. But aside from being able to market direct injection, Audi’s road-going diesels were nothing like the racecar. That could not stand. According to a retrospective at PistonHeads, Audi management ordered the creation of an engine inspired by the competition powerplant.
According to Motor Trend, Audi knew that the creation of the V12 TDI was never going to make it money. Instead, it was a halo product to bring people into showrooms and at least something physical that Audi could say was inspired by its dominating racer. In November 2006, Audi announced that its team was working on a 500 HP V12 to go into the Q7 SUV for consumers to buy.
Reportedly, Audi had a second plan for the V12 TDI and that was to place it into Audi’s then flagship supercar, the R8. It was only a fitting combination. Some prototype R8s were built with the V12 TDI in 2008, and our Matt Hardigree got to drive it in city traffic. Sadly, Audi figured out that the costs associated with making the massive and heavy V12 diesel fit into a production R8 would have been too expensive. Thankfully, Audi was also working on putting this engine into the Q7, so development on that continued.
Engineering trade magazine MTZ notes that the V12 TDI is not really just the racing engine detuned for road use. Instead, the V12 TDI was really Audi taking much of its engineering to the limit. The V12 TDI featured a 60-degree bank angle and overall design somewhat similar to the V6 TDI and the V8 TDI that Audi already had in production. This meant a relatively compact design with drive chains in the rear and a vermicular graphite cast iron block. Like other TDIs, the V12 also had 90mm cylinder spacing and what MTZ called a similar cylinder head gas flow concept as the other TDIs.
However, the V12 TDI wasn’t just a V6 TDI with the cylinders doubled up. As MTZ explains, the 60-degree bank angle was unique to the V12 TDI. The engine also got its fuel from a Bosch common rail injection system firing fuel at 29,000 PSI with Piezo injectors and the engine needed two CP 4.2 high-pressure fuel pumps to run.
MTZ continues that it wasn’t enough that Audi’s engineers built a powerful V12. This engine had to deliver crazy power but not guzzle fuel. It had to be able to fit into an existing engine bay and borrow as much as it could from the Audi parts bin. Of course, we are talking about an Audi, so it also had to be buttery smooth.
MTZ notes that the V12 TDI had four valves per cylinder and a crankcase as well as main bearings from the proven V6 TDI platform but adapted for the 60-degree bank angle. The V6 TDI’s cast aluminum pistons make a return here as well.
What’s really fascinating here is just how different the Audi V12 TDI is compared to the Volkswagen V10 TDI. Both of these engines are modern mills from a couple of companies under the same umbrella. I wouldn’t have faulted you for thinking that the V12 was just a V10 with two more cylinders. However, because Audi developed the V12 on the existing V TDI platform, it’s different than the more bespoke V10 TDI from VW.
I mentioned one huge difference earlier. The VW V10 TDI has a beautiful gear drive system on the back of its engine. But the more powerful V12 TDI? It has a chain drive system for its timing and other main engine components like the oil pump. This also means another huge difference between the V10 and the V12. While the V10 uses that same gear drive system to power all ancillaries like the alternator and power steering, the V12 has an old-school belt.
Audi was clever to borrow as much tech as it could from its existing engines. While the V12 TDI has more impressive output numbers than the VW V10 TDI, the engineers at VW seemingly took a far more convoluted path to create their engine.
The Audi Q7 V12 TDI made its debut in 2008 and it had some huge numbers behind it. The engine was nominally 5.9 liters and thanks to the help of a pair of Garrett GT 22 variable geometry turbos, the V12 TDI was advertised to make 493 HP and 738 lb-ft of torque. To put that into perspective, a 2008 Ford Super Duty F-250 Power Stroke had 350 HP and 650 lb-ft of torque. Audi further said that the Q7 V12 TDI, which was by no means a small SUV, could sprint to 60 mph in just 5.5 seconds with this engine.
Even cooler was that Audi expected to bring the Q7 V12 TDI to America. Just like with the R8 V12 TDI prototype, Americans got to drive the hopped-up Q7, too. Here’s what Car and Driver said:
On the road, few cars can keep up. Audi says the 0-to-62-mph sprint takes 5.5 seconds, and—more impressive—112 mph is achieved in 15.7 seconds. These figures, which we haven’t verified with test equipment, seem absolutely credible. Power is instantly available. Push the throttle, and you get treated to an evil growl as the Q7 lurches forward. We were surprised at the elevated sound level. Audi wants it that way, though, and in fact, it’s almost completely designed into the exhaust system. The 6.0-liter V-12 works smoothly and quietly otherwise.
At 155 mph, a governor kicks in. The theoretical top speed is 171 mph in standard configuration, and 176 mph would be possible with minor tweaks. But the cutoff is fine with us, since it is part of a voluntary agreement by the German auto industry that has thus far helped to keep the autobahn unfettered by an overall speed limit. After all, we prefer a real 155 mph to a theoretical 176. This 6.0-liter V-12 is completely new, but it shares components with Audi’s family of V-6, V-8, and V-10 engines. Audi wants you to believe this engine is derived from that of the Le Mans–winning R10 TDI race car, but there are few commonalities besides the high-pressure common-rail injection system.
Despite this SUV’s considerable heft—5700-plus pounds—it feels light and agile. The steering setup is more direct than in other Q7 models, and the adaptive air suspension can be dialed into a dynamic setting that pushes the capabilities beyond typical-SUV territory. In this setting, body roll is almost nonexistent. As for the Quattro all-wheel-drive system, the power distribution is flexible, but the standard setting is 40 percent front and 60 percent rear.
By all reports, Audi essentially took its flagship SUV and turned it into a supercar. The Q7 was a great pick for this engine, too.
Development started in 2002 and the Q7 was built on the VW Group PL71 platform, which made it a sibling of the early Volkswagen Touareg and Porsche Cayenne. However, while those two vehicles were mid-size super SUVs, the Q7 went for high luxury. At 118 inches, it was 6 inches longer than a Touareg. Like its siblings, the Q7 had a permanent four-wheel-drive system, but unlike its siblings, it lacked a low-range gearbox and didn’t have a fancy off-road version that jacked it high and covered the undercarriage in skid plates. Even the Q7’s styling was wildly different than the Cayenne and the Touareg. While those tried to be butch German off-roaders, the Q7 borrowed its looks from the Audi Pikes Peak Quattro concept car.
So, this thing sounds like the holy grail of luxury SUVs. It makes more power than a diesel truck, is as fast as a sports car, and cups you in warm luxury. What went wrong? Well, as Car and Driver noted in its review, the darn thing had an asking price of the equivalent $185,000, which made it the most expensive Audi on the planet at the time.
Do you know what else was going on in 2008 and 2009? Audi’s timing was unfortunate because it launched its halo car right on time for a global financial crisis. Audi would end up canning its plans to sell these things in America. And it wasn’t just the economy. Audi didn’t think there was a big enough market for diesel luxobarges in America. Even worse, Audi had also considered giving us a Q7 hybrid and then canned that as well.
Ultimately, diesel fans were thrown a smaller bone with the 3.0 V6 TDI and that was that.
It Failed Even As A Halo Car
Things weren’t much better in Europe where these vehicles did sell. The folks of PistonHeads write that the Q7 V12 TDI was £96,200 before any options. But again, this made sense. The V12 TDI was always supposed to be a halo, not a money maker. Still, it’s clear that fewer people were interested in V12 goodness than Audi expected. The V12 also wasn’t as economical as expected, either. The engine spewed 300g/km of CO2 and only 25 mpg combined, and I’m not talking about U.S. mpg numbers here.
While production numbers across Europe have not been reported, UK sales numbers were. The Q7 V12 TDI was sold for just four years. Over that time, Audi expected to sell 40 a year in the UK. Instead, just 50 were sold in total. Amazingly, I have found a few of these for sale and it looks like they could be had for around the equivalent of $34,637. Of course, the harder thing would be convincing the American feds to let one of these in. But if worldwide production was low enough, I could see one possibly getting in.
Another interesting fact: Thanks to the sharp decline in diesel passenger cars (in part caused by Piëch and Dieselgate), the V12 TDI is the only production engine of its kind. No other production car in history has had a V12 diesel and it’s unlikely we’ll see another one ever again. The Audi V12 TDI was definitely a vehicle for another time. The diesel was flowing high and it seemed everyone thought diesel was the future. Now we know that’s not the case. But at least some engineers at Audi got to have some fun creating one of the wildest engines to be fitted into a modern production car.
Maybe 25 miles per UK gallon sounds wasteful compared to other modern cars. but swapping one of those into a Fleetwood Talisman, a Givenchy Mark V or a bad-engined but otherwise well-kept version of my mom’s ’76 Custom Cruiser clamshell would make them more efficient and faster while still providing more luscious and creamy torque than could have been imagined when they were new. And reliability and serviceability
wouldmightcouldimprovestay about the same or maybe a little betterbe not enough worse tomake it an awful ideadissuade one from doing it, with a little help from a disordered mind and some extra time to fill after the departure of one’s spouse.[Pushed glasses up nose]
Actually, the Cummins sponsored car that won the 1987 Indianapolis 500 – giving Al Unser, Sr. his record-tying fourth win – was fueled by methanol, not gasoline. Gasoline was effectively banned from Indy after the horrific accident during the 1964 race.
I had a first gen Q7 with the V8. It was awesome. AWD, 0-60 in a shade over 7 seconds. All the options. It towed 6000lbs and weighed 6600lbs.
I cannot imagine how insane it might have been to drive a V12 diesel.
Only a 15 year import limit for Canada though…
Back when I was on Facebook I saw one of these for sale. An Audi exclusive brown on brown. Truly the holy grail. https://spots.ag/2024/01/14/audi-q7-v12-tdi-c468014012024004203_6.jpg?1705189381
It is impressive how much effort the VW Group put into halo diesel engines, yet just absolutely ruined the perception of diesel engines with the emissions scandal. Seemingly permanently, no less.
It would be as if Toyota made an early Lexus LS that could go untold hundreds of thousands of miles nearly perfectly, but made a 1992 Camry as unreliable as possible.
Very few people remember or care about the rotary powered 787B that won the 24 Hours of Lemans in 1991, but the brutal reliability of the RX-8 ruined rotary engines in the perception of the engine in the minds of owners and the public.
I get that VW made a cool thing, but it mostly serves to remind me that VW was the same author of that thing’s demise not even a few years later. The hubris of the Piech era is almost appalling in equal measure as it was amazing. A shame the appalling bits tended to just ruin things for normal people.
This is exactly what is happening to modern EVs across the board. Make expensive, oversized, extremely complicated luxury vehicles with mediocre CdA values that in the best of circumstances could be matched by classic small European sports cars from 60 years ago, with giant/expensive/heavy battery packs designed to prevent easy access and repair, with all of the car’s electronics and features integrated into an annoying touchscreen where all of the electronics and powertrain components have an encrypted software locking out non-manufacturer access/repairs.
Thus, the manufacturers have taken a technology which could allow affordable, simple, easily-repaired, efficient, money-saving, long-range electric automobile options that could last a human lifetime with minimal upkeep/hassle onto the market, and instead use it to make overpriced, tech-laden, complicated, un-economically repairable, disposable landfill fodder that will become useless soon after the warranty period ends, all in the name of short term profits and maximizing extraction of money from customers, all while claiming that creating all of this energy-intensive, disposable, toxic crap meant to end up in a landfill and then trying to force it on everyone is helping to save the planet.
Aside from culture war lunacy, there’s many valid reasons middle America doesn’t want EVs, that have everything to do with the cost, upkeep, complexity, and lack of reparability of the offerings available. There’s no valid reason why a highway-capable EV should be any more complicated to repair than a 1970s golf cart, or for a sedan or wagon to use any more than 0.180 kWh/mile to cruise 70 mph. Greed is the reason we don’t have simple, inexpensive, efficient EVs. The tech was already there in the mid 1990s.
A good, rock-solid reliable EV that has an entry level price, comfortably seats a family, offers an honest 200+ mile highway range, and will also put the longevity and reliability of a Ford Crown Victoria or 1980s diesel Mercedes to shame is not rocket science. It was possible almost 3 decades ago, from a technological standpoint. What it will require is throwing convention away regarding styling in favor of low aero drag and dealing with the possible cannibalization of sales from more profitable vehicles.
If the auto manufacturers don’t reverse course on this, they deserve to go bankrupt. Let the Chinese in without tariffs. That will give the USA manufacturers a reality slap good and quick.
This engine deserves to be in a sub-2,500 lb streamliner. Get 50+ mpg at 70 mph with a V12 capable of pushing the vehicle to 250+ mph.
There’s got to be a Bonneville class it would dominate.
I love German cars, and have owned a PILE of them. Love how they feel to drive, usually like how they look (in the past anyway), and they have always been a good ownership experience for me, largely because I avoid the dick waving editions. And I just don’t get these stupid dick-waving versions. This really does nothing useful that a much, much cheaper and simpler V6 TDI would do other than spend your money. And I guess show that you CAN spend that money. And with a lot less weight in the nose, handle better.
As I have said here many times, if I just want my internal organs re-arranged by g-forces, a season ticket to Six-Flags is a whole lot cheaper. And safer for my health, license, and insurance costs.
The 87 Indy winner with “Big Al” was sponsored by Cummins and their subsidiary Holset Turbocharger, but it was powered by the same Cosworth DFX that most of the field ran.
Was about to say the same here. I knew about the Ilmor pushrod engine, so if a diesel has won in 1987 I’d surely have heard of it.
I still think these Q7s are some of the best looking SUV’s of all time. Audi’s styling of that era has aged incredibly well.
The interior design of this era fascinated me. Just absolutely gorgeous and so well put together. That cockpit dashboard that flows into the center stack. That’s when I started paying attention to Audi. It has, and will continue to, age gracefully. Yet if you so desire it can be upgraded with a larger screen with AA or CP. It is perfection.
I saw one driving between Amsterdam and Antwerp in 2009 and legitimately thought the badge was fake until I looked it up later.