Audi R10 TDI

At the beginning of the 2006 season, homologation rules for Le Mans Prototypes (LMP) cars were changed, for the LMP1 class, an increase in minimum weight from 900 kg to 925 kg was mandated. While officially this was to allow closed top prototypes to run with air-conditioning (as this would have added weight over open top cars), some have speculated that this was done at the behest of Audi to allow the R10 to be competitive.[6]

The R10 TDI in the 2006 12 Hours of Sebring was overweight at 935 kg (2,061.3 lb), preventing engineers from using ballast to optimize handling and balance.[7]

Audi's decision to use a diesel engine emphasizes the commercial success of Turbocharged Direct Injection (TDI) turbodiesel engine (and its competitors) on Europe's roads. Diesels have been successfully used in other forms of racing as well, as their broad power band and fuel economy can prove advantageous, while in turn, the higher weight and lower rotational speed of the engine requiring new power transmissions are the disadvantages. The rules had to accommodate the need for a high capacity engine with a turbocharger and high boost, whereas both possibilities are no longer allowed for gasoline engines, as these had developed over 1,000 hp (746 kW; 1,014 PS) in several race series of the past.

It is not, however, the first diesel to be raced at Le Mans. The first diesel-engined car to qualify and race in the 24-hour event was a French entry in 1949, the first race held after the Second World War. The car was the Delettrez Diesel entered by brothers Jean and Jacques Delettrez, and was a 4395 cc 6-cylinder. It did not finish, running out of fuel about half way into the race.

Delettrez entered again in 1950, as did another diesel car, the MAP. Again, both cars did not finish due to engine problems, a cooling system leak in the case of the MAP. The MAP was interesting in that it was the first mid-engined car to race at Le Mans; the engine was located immediately behind the driver, and was a four-cylinder opposed piston two-stroke with rocking levers connected to a single crank, similar to the later Commer TS3 engine.[12]

In 2004, a Lola equipped with a Caterpillar re-badged V10 TDI ran for a few hours before breaking its clutch. Peugeot competed with its new diesel effort in 2007 in its 908 HDi FAP race car.

On 18 March 2006, the #2 Audi R10 won the 54th annual 12 Hours of Sebring after earning pole position by setting a qualifying record. The #1 car did not finish due to an overheating problem. On the day after the Sebring victory an R10 flipped over during testing while running through Turn One. However the R10 would not complete the most of the season. The Audi R8, completed most of the season with the R10 returning to race in the different Le Mans Races (Le Mans 24 Hrs, Petit Le Mans etc.)

On 18 June 2006, the #8 Audi R10 placed first at the 2006 24 Hours of Le Mans, completing 380 laps, more than the R8 did, but less than the record set in 1971. The #7 Audi R10, which set fastest lap times in practice and race, came in third after suffering injector pump damage, completing 367 laps.

Due to the sheer Audi dominance, the IMSA instantly made changes to the rules in the season. The Audi was not pegged back but competitors were helped to push their pace up to the Audi level. All LMP1 petrols were to be run at 860 kg and had their fuel tank increased to 95 liters. Dyson, Zytek, Creation and Porsche all have outqualified the Audi at one point during the season, but Audi were able to overcome the restriction deficit to take every win.

On 30 September 2006, the #2 Audi R10 won the 9th annual Petit Le Mans endurance race at Road Atlanta in Georgia. The win was seventh in a row for Audi in Petit Le Mans, but first for the R10 model. The #1 car was not running at the finish due to late race collision with another car resulting in damaged front suspension. #1 car was still classified in seventh place overall.

Audi R10, Le Mans 2007

On 17 March 2007, the #2 Audi R10 won the 55th annual 12 Hours of Sebring. The #1 car finished 2nd in its class (LMP1) and 4th overall.[13] The R10 remained undefeated in American Le Mans Series competition until April 14, 2007, at the Long Beach Grand Prix; where it finished seventh overall to the Porsche RS Spyders of Penske and Dyson Racing. The car still won the LMP1 class.

IMSA had made changes to the category again. Under pressure from Audi and the ACO, LMP1 cars were now meant to have at least a 1.5% performance advantage over LMP2. The ACO reserves the right to make changes to specific cars if this was not happening. Throughout the season, the Penske Porsche RS Spyder won 8 overall victories against the Audi R10 which only won 4. The ALMS track nature suited the lighter and more nimble P2 cars more, which was evident as Audi loses time in the corners to the Porsche. At Petit Le Mans, Capello was able to use his speed advantage to overtake Dumas in the last half an hour. McNish and Capello won by 0.9 seconds. At Laguna Seca they won over the #7 Porsche by 0.4 seconds

It is undefeated at the 24 hours of Le Mans, having successfully defended its 2006 victory. On June 17, 2007, the #1 R10 finished first overall, overcoming the loss of two of the three team cars and defeating a new challenge from the Peugeot 908 HDi FAP diesels. The #3 Audi was put out of the race by driver error, crashing into a wall, whereas the #2 car suffered a wheel failure at approximately 300 km/h (186 mph) and collided with a barrier. Video pictures showed the car being dropped prematurely during a prior pit stop with the wheel in question not being properly attached, but Audi's official statement is that the incident was not the fault of the pitcrew, as the car had been on track for over 50 minutes since its tires were last changed. At Le Mans it was obvious that the R10 was faster than the Peugeot 908 on the straights and much more stable in the corners.

According to ACO's official data, the Audi R10 TDi reached a top speed of 329 km/h (204 mph) on the Mulsanne Straight in the 2006 race. In 2007, while changing their pace in order to beat Peugeot, the Audi R10 TDi hit 339 km/h (211 mph) on the Mulsanne Straight, which was faster than any other car in the race. The R10 TDi also set the best lap of the race at 3:27.176. The car seems to have managed a top speed of 354 km/h (220 mph) in practice at Le Mans in 2007, which would be the absolute speed record of an LMP car at Le Mans (since LMP's only run from the introduction of the two Mulsanne chicanes on). At the car's official launch in Paris, 2006, the Audi R10 TDi was presented as capable of reaching a top speed in the region of 370 km/h (230 mph)

For the 2008 season, Audi entered the Le Mans Series for the first time. Joest Racing entered two cars to compete against Peugeot's two-car entry over the five race season. Peugeot led the championships early, winning the first three races prior to the 24 Hours of Le Mans. A new sub-wing was introduced at Spa. This maintains the same level of downforce but less drag.

At Le Mans, Audi won for their third consecutive time with the R10. The #2 car driven by Rinaldo Capello, Allan McNish and Tom Kristensen took the chequered flag on lap 381 ahead of the #7 Peugeot, with a margin of just over 4 minutes. The other two Audi entries finished fourth and sixth overall. Peugeot brought their seasoned 908 HDi FAP and qualified within the 3:18 range while Audi struggled to get under the 3:23 mark. In the race itself the Peugeot was still up to 3.5 seconds a lap faster but quick pit work by Audi and the superior performance by the R10 in the rain saw Audi winning Le Mans.

Returning to the Le Mans Series for the final two races of the year, Peugeot won once again at the Nürburgring and maintaining their lead in the championships. However, accidents for Peugeot and a win by the #1 Audi of Rinaldo Capello and Allan McNish at the Silverstone finale allowed the Audi team to win the Constructors Championship, while the #2 Audi of Mike Rockenfeller and Alexandre Prémat earned the Drivers and Teams Championships.

Audi also continued their participation in the American Le Mans Series. As in the year before, Audi fought against the Penske Racing Porsches for overall race wins, but unlike before they now had to contend with the multiple Acura teams. Porsche managed to end Audi's streak of seven straight victories at the 12 Hours of Sebring, but Audi rebounded with overall wins in the next two events. Three more overall victories were earned by Audi by time the series reached the Detroit Sports Car Challenge. Audi not only failed to win the race overall, but following a rule infraction, neither car finished in the LMP1 category. This was the first time that the Audi R10 failed to win in LMP1, and the first LMP1 loss by Audi since 2005. At Petit Le Mans, Allan McNish overtook Christian Klien in the Peugeot on the penultimate lap and held on to the win.

Kolles' R10 TDI competing in its debut race, the 2009 1000 km of Catalunya

In the 2009 season, the R10 TDI was replaced by the R15 TDI with a smaller, lighter, more-efficient TDI engine; however, Audi concentrated on the 24 Hours of Le Mans and Deutsche Tourenwagen Masters (DTM; German Touring Car Masters) efforts. The new car, however, ran in the 2009 12 Hours of Sebring before preparing for Le Mans. The Audi R10's wing was limited by the 2009 regulations. In early 2009, Colin Kolles announced that his team will run privately entered Audi R10 TDI's in that year's 24 Hours of Le Mans, and possibly the Le Mans Series. The deal included factory assistance for servicing the cars.[14] At Le Mans, the Audi R10 best finished 7th overall, a few laps down on the highest petrol finisher Lola-Aston Martin which ranked 4th overall.

Kolles fielded 2 Audi R10 in their final year at the Le Mans 24 Hours, on 14 June 2010. Unlike the factory Audi and Peugeot LMP1, the Kolles R10 was not hampered by the new restrictor regulations which should have shaved off 60 bhp from the diesel-powered prototypes. The cars qualified 3:30, just behind the two Lola Astons. Both cars failed to finish because too much strain from torque was put onto the gearbox.