The 12-hour race at Sebring is one of the most historic--and most daunting--of endurance racing challenges offered on the North American continent, and not just because of the duration or the track. The competition, especially in the LMP1 division of American Le Mans Series racing, is tough.

The Audi R18 e-tron quattro aims to be the toughest of the bunch, continuing Audi's global dominance of endurance racing for the better part of the last decade, excepting a few challenges from Peugeot.

As Audi's newest take on facing the challenges of endurance racing, the R18 e-tron quattro uses hybrid power and a TDI diesel engine to maximize mileage while maintaining a balance between weight and handling. One car will run in 2012 spec, while the second will be an updated prototype, likely testing improvements ahead of this year's Le Mans 24 Hour race.

The car has already been tested in competition in 2012 (including a win at the 24 Hours of Le Mans last year), but the run at the Sebring 12 Hours will be important for one big reason: it's the last time it'll likely run there.

Why? Because of the merger of ALMS and Grand-Am, which will see the disappearance of the LMP1 category from American competition.

It's also important to Audi for historic reasons: "Sebring is where Audi’s sports car era that has been so successful began. We expect that with two current hybrid models we’ll be battling for overall victory at the 12-hour race for the last time this year," said head of Audi motorsport Dr. Wolfgang Ullrich. "At the same time, on the fringes of the race, the fans can look forward to seeing four other race cars and several race drivers who made history at Sebring with Audi."

One of the R18 e-tron quattro drivers will be Danish Le Mans racing legend Tom Kristensen, the current record holder for the Sebring 12 Hour and eight-time winner of the 24 Hours of Le Mans, six of those times behind the wheel of an Audi.