Top Gear's coolest racing cars: Audi R10 TDI

So relentless has Audi’s racing Technik been throughout the 21^st century, it’s difficult to deny that a little Vorsprung fatigue hasn’t crept in. Even when the team lacked absolute pace, which didn’t happen very often, the wheels rarely fell off the wagon – literally or metaphorically. "It’s down to the five ‘Ps," nine-times, fully paid-up Le Mans-winning legend and Audi pilote Tom Kristensen noted. "Proper preparation prevents poor performance." (A technical variation on ‘Peter Piper picked a peck of pickled pepper’, and easier to say.)

Yet TG.com is old and ugly enough to remember the era before Audi entered top-flight endurance racing in 1999, and began waging a campaign of righteous terror on the sport’s big guns. We also remember how the racing world reacted when the Germans responded to a big mid-Noughties rule change, having chalked up five Le Mans victories and Lord knows how many other wins, and switched to diesel from 2006. Diesel? Was nothing sacred? The times they were a-changing…

Needless to say, the unit that lay at the heart of the R10 TDI was no ordinary oil-burner. At 5.5-litres, it ran the maximum capacity permitted by the ACO’s new rules. This gopping great lump, ingeniously all-aluminium rather than cast-iron, had 12 cylinders, direct injection, and twin turbos, the net result being in excess of 650bhp (plus another 150 on a 10-second overboost). But the real doozy, of course, was the amount of torque it summoned: more than 811lb ft from 3000rpm, positing the sort of sea-change in motorsport that only comes along once-in-a-generation. 

To go with the devilry of the new power unit, the R10 also looked markedly different from its predecessors. Accommodating that vast engine meant lengthening the wheelbase, which not only helped counter-act the diesel’s punitive weight, it also gave the Audi a fabulous silhouette. The carbon-clothed wishbones on the front suspension were visible, and cowling was added to the brakes to improve cooling and aero. Italian stalwarts Dallara handled the car’s build, and its design included a quick-change front and rear section. Guffing out billowing clouds of black smoke would hardly chime with the R10’s pro-diesel remit, so an expensive particulate filter made of a chemically treated ceramic was fitted. 

Compared to the current generation of rather disharmonious hybrid beasts, the R10 TDI isn’t just a thing of aesthetic wonder, it could also lay claim to being the definitive Noughties open-cockpit endurance racer. We don’t recall thinking so at the time, but it’s actually very pretty (as all the coolest racing cars must be).

There was no steadily upward results curve for the R10: this was a winner out of the box. It was revealed to the world in Paris late in 2005, following a secret squirrel development programme during which Audi pushed its partners and suppliers to the max (Mahle had to devise special magic pistons, for example). The R10 qualified first and second at Sebring, and went on to win, with Allan McNish, Tom Kristensen and Dindo Capello driving. This was despite starting from the pit-lane, following a last-gasp repair job on a broken heat exchanger. From 35^th and last, the no.2 R10 was up into second position after just 30 minutes, sending an ominous signal to Audi’s rivals about the car’s pace and indomitable character. 

It was a similar story at Le Mans that June, during which an R10 TDI led the field for the duration of the race. After 380 laps – a new distance record at the time – Frank Biela, Emanuele Pirro and Marco Werner took the historic, pioneering win. Kristensen, meanwhile, set the fastest lap of the race, 3min 31.2 secs, while also managing 16 laps on a single load of fuel. Fast and frugal…

And quiet. TG.com remembers watching by the Dunlop Bridge as the R10s went by, emitting little more than a whooshy turbo whistle, but travelling at a velocity out of kilter with the noise. If spectators had to get used to this stealthy speed/sound unusualness, it was no less discombobulating for the drivers. One of the instrument displays flashed up whatever gear they were in, and above 100mph the wind noise drowned out everything else. The R10 TDI demanded recalibration from all involved. 

It also took three consecutive wins at Le Mans, in 2006, ’07, and ’08, seeing off a major challenge from Peugeot in the process. Its 908 HDi FAP was also a spectacular machine, and notably faster. But Audi prevailed. There’s a sixth ‘P’ for you right there, Tom…

Years: 2006-2009
Designed by: Gioacchino Colombo, Valerio Colotti
Drivers: Alan McNish, Tom Kristensen, Frank Biela, Dindo Capello, Emanuele Pirro, Marco Werner
Engine: 5.5-litre V12, 650bhp @ 5000rpm
Weight: 925kg
Stand-out moment: Le Mans 2006, first diesel win