When we write about diesel vehicles, we’re typically covering the makes/models that had massive production numbers. We love our TDIs, common-rail Mercedes, and Jeep CRDs, but for a moment we’re shifting our focus to the diesels that you would rarely see out in the world.

BMW Low-Production Models

In the United States, diesel passenger vehicles account for less than 3.0% of all registered passenger vehicles. One of the rarest models you can find (or rather, cannot find) is the BMW 740Ld xDrive.

• Only offered for two model years
• Utilized the N57 that also came in the X5 35d
• Paired flagship styling with a fuel-efficient diesel engine
• All Wheel Drive, long-wheelbase

While the 740Ld could hold 21 gallons of fuel and was optimized for comfort on long drives, the timing of its release with Dieselgate caused demand to shrink. It is estimated that only a few hundred units were sold in the US market.

Even more difficult to find is the BMW 540d xDrive. Built on the G30 chassis and only offered for the 2018 model year, there were only 298 units brought to the United States. These had the potential to come with the M Sport package and could even be optioned with night vision with pedestrian detection. The 540d was also the only vehicle ever sold in the United States with BMW’s B57 diesel engine.

Honorable mention: Another hard to find vehicle featuring a BMW diesel engine is actually a motorhome. The M21 2.4L inline six was the first diesel engine made by BMW, and several hundred of them were installed in Vixen 21 TD RVs. A total of 415 Vixen motorhomes were paired with the BMW turbodiesel.

Volkswagen Special Purpose TDIs

This one goes without saying: The Jetta TDI Cup Edition is one of the most desirable TDIs put into production. Volkswagen created this special edition model to celebrate the success of the TDI Cup racing series. Only 1,501 units were produced and many were later bought back.

The series was sanctioned by the Sports Car Club of America and featured 30 drivers developing their racing skills, but the actual racing spec Jettas differed from the street version. The race cars received the European Golf GTD 2.0L engine with a CR170 turbocharger, while the street edition came with the US market 140 hp 2.0L engine. Plus the race cars received about 400 pounds of weight reduction. Less than 600 of the 1,501 units were fitted with a manual transmission while 60% of the units came with a DSG.

These Cup Edition cars were involved in Dieselgate and now it is estimated that 300-350 of these cars remain.

Speaking of racing, Volkswagen was also having success in the world of rally racing during this time. VW Motorsport entered the Dakar Rally in 2004 with custom-built tubular-frame prototype Touaregs, PLUS a 5-cylinder 2.3L TDI engine. These rally machines saw roughly 405 ft-lbs of Torque and scored third place overall in the 2005 Dakar Rally. That also named Volkswagen as the first diesel to score a podium finish in the Dakar Rally.

VW went on to race rally Touaregs with an upgraded 2.5L 5 cylinder twin-turbo TDI engine from 2006 to 2010. This is the vehicle that secured Volkswagen’s first two overall Dakar victories in 2009 and 2010. In 2011 they further refined the 2.5L twin turbo TDI with optimized cooling & aerodynamics. This led to a hat trick where the top three overall podium winners were all driving VW Race Touaregs in the 2011 Dakar Rally.

Honorable mention: Stanley The Self Driving Touareg. This article would not be complete without reference to a diesel-powered Volkswagen that helped advance technology. A team from Stanford University partnered with Volkswagen Electronics Research Laboratory to compete in a challenge set by DARPA. The challenge was to complete a 132 mile desert course across the Mojave Desert. But here’s the catch: the challenge was meant for autonomous driving. That meant that in 2005, Stanford alongside Volkswagen was able to develop a self-driving system that successfully crossed the desert without a human at the wheel.

Stanley the Touareg was a European model powered by a 2.5L TDI engine and VW donated two Touaregs to Stanford to complete in the challenge. The drivetrain was untouched, instead Standford focused its efforts on modifying the drive-by-wire system to work with their computer and added reinforced skidplates under the vehicle. The trunk looked like a server rack with 6 computer systems and on the roof they fitted 5 LiDAR units to map the terrain. Also long-range radar, accurate GPS, and camera systems aided in navigation and was the reason Stanley was able to complete the course when other teams could not. Stanford University was victorious and brought home a prize of $2,000,000 which was dispersed to graduate student fellowships and to further intelligent vehicular research. This challenge left Volkswagen with none of the prize money but all of the experience that went into creating this autonomous driving system.

Next up, Audi!

Audi

Many people associate Audi’s fame with the creation of Quattro, but they hold another illustrious title. They are the only manufacturer to put a V12 diesel passenger car into production. Ever.

The Audi Q7 6.0L V12 TDI (who expected to see 6.0L, V12, and TDI all in the same sentence?) is capable of 500 hp and 1000 Nm of Torque, or 738 ft-lbs. These featured the Quattro AWD system and an automatic 6-spd Tiptronic transmission because it was one of the few gearboxes available that could reliably handle the 1,000 Nm of torque. It is estimated that only 500 to 1,000 units were ever made from 2008 to 2012 and was comparable to the price of a new Audi R8. And unfortunately, this Q7 was never brought to the United States (but we weren’t surprised).

Additionally, Audi applied their diesel technology to racing. The R10 TDI was unveiled to the public in December 2005 and remained undefeated during its first season of racing in LMP1. The project was authorized by none other than the current chairman of the Volkswagen Group: Ferdinand Piech and the engine was a 5.5L V12 TDI. The common rail injected engine was twin turbocharged and was the result of serious re-engineering and experimentation with this new realm of TDI power. The very notion of a cast iron block was re-engineered with an aluminum-silicone alloy to reflect the racing philosophy of saving weight. The R10 even featured specialised DPFs that were so efficient that they emitted nearly transparent exhaust gas.

“In the end we simply took advantage from the low consumption of the TDI engine. Today we really used the diesel until the very last drop. This was an impressive demonstration of Audi TDI Power.”

Dr. Wolfgang Ullrich (Head of Audi Motorsport)

These successful developments paved the way for Audi to create an R15 in 2009 with a 5.5L V10 TDI that reduced weight from it’s V12 predecessor. Two years later, Audi transitioned to a smaller 3.7L V6 TDI engine in the Audi R18 to comply with regulations. In 2012, the R18 was succeeded by the R18 e-tron Quattro and was the first hybrid vehicle to win at Le Mans. This vehicle had the same basic V6 TDI structure but with the addition of hybrid tech.

Mercedes C111 Experiments

In the 1960s and 1970s, Daimler-Benz was experimenting with new engine technology and vehicle design that was intended to break performance records. They constructed these futuristic gullwing prototypes and paired a variety of powertrains, including the OM617. Other prototypes employed a naturally aspirated V8 gasoline engine and rotary engines with either 3 or 4 rotors.

The C111-III with the OM617 achieved 228 hp / 401 nm of Torque which empowered the vehicle to reach a top speed of 210 mph. This was a testament to the power and simplicity of manually injected diesel engines, with the added engineering of an aerodynamic chassis. We also wanted to point out the top speed reported for a 4 rotor C111 was only 186 mph. The diesel prototypes set a record time at the Nardo test ring and achieved their top speed on that track.

In terms of numbers, the total production was only 16 cars. According to an episode of Jay Leno’s Garage with a representative from Mercedes-Benz Classic Center, there were 13 made with the Wankel rotary engines, only two individual cars that had the OM617 turbodiesel engine, and one car with the gasoline V8.

In Conclusion

If you’re familiar with diesels, you’ll know that often the most appealing models never made it to the US market. We wanted to take a break from that sentiment and highlight truly unique diesels that broke records and pushed the limits of what is possible. Use this as a starting point for any rabbit holes you go down, we guarantee the vehicles mentioned above are worth it!