If Audi needed any further proof that switching to diesel fuel was a shrewd move, then victory at the season ending round of the American Le Mans Series at Laguna Seca was certainly a triumph for frugality over raw speed.

Indeed, although arguably not the quickest car on the circuit, Dindo Capello and Allan McNish were able to keep in contact with race leaders Zytek and Creation for the early part of the race, but duly moved into the lead when their better fuel economy allowed them to run longer on their first stint.

However, their hopes looked almost certainly dashed when McNish suffered contact with another competitor, damaging the front of his car and receiving a stop-go penalty for causing an 'avoidable accident'.

With this in mind, Audi switched to a risky strategy of fuelling McNish up to the end with 64 laps of the remaining, well over a third of the race distance, turning the revs down on his car in a bid to eke out the last remaining drops of diesel fuel available.

Moving into the lead when others in front duly pitted for the final time, McNish stayed out and despite some rather fraught moments on the pit wall as the race closed, he was able to coast over the finish line to uphold the R10's 100 per cent winning record that started back at the Sebring 12 Hours.

"It was a thrilling race, from start to finish and never an easy moment,” McNish. “We had a number of brushes with other cars, more than in any other ALMS race this season, including a stop-go penalty for an unfortunate situation – the incident was no one's fault. After that, we just had to throw the dice on strategy and thankfully it worked out for us.

“To be able to race around here for 90 minutes on one tank of diesel fuel is just amazing. I had to work quite hard on fuel saving in the closing stages but without the TDI technology, we'd never have made it without another pit-stop.”