Piloting the winning Phoenix Racing cars were international drivers Christer Jöns, Christopher Mies and Darryl O'Young, fighting to victory after a spin briefly relegated the #1 car to third place.
The win marks the car's second in as many years at the mountain, with rain and thick fog making for a tougher race than last year's event.
Victory on Sunday capped off a perfect weekend for the trio, after setting the fastest qualifying time on Saturday and taking pole position for the big race.
It was also the 119th win since the launch of the Audi Sport customer racing programme three years ago.
"After this weekend we can be more than happy because we experienced a pretty rough day. We were fighting for twelve hours straight, from the beginning through to the end, and we did so in difficult overall conditions," Customer Sport quattro GmbH boss Romolo Liebchen said.
"We won but on the other hand two of the Audi cars did not finish due to accidents - including our strong Australian car. In the end, one R8 LMS made it, and our youngsters prevailed with a really cool showing."
Phoenix Racing's second car, piloted by Australians Mark Eddy, Craig Lowndes and Warren Luff, put in a strong opening effort, battling to the front of the field after starting at fifth and leading the race in hours four and five.
In the end, the #2 car lost four laps after a severed refueling hose led to a five-minute penalty, and was later forced to retire after Mark Eddy collided with a concrete barrier.
"In the race both Audi cars were running at the front some of the time but as the race progressed conditions became more difficult due to rain and fog," Eddy said.
"Unfortunately, I then had the accident on the mountain and we retired. I let a warning message on the cockpit display briefly distract me."
Audi has now recorded four major endurance victories within twelve months, including two successes at the Bathurst 12 Hours and one victory each at the 24-hour races on the Belgian circuits at Spa and Zolder, plus GT3 class victory at the Nürburgring 24 Hours.
- Jöns/Mies/O’Young (Audi R8 LMS), 270 laps in 12h 03m 31.375s
- Slade/Bleekemolen/Hackett/Curtis (Mercedes) + 1m 13.284s
- Sun/Baird/Griffin (Ferrari) - 2 laps
- Tinkler/Johnson/Richards (Porsche) - 16 laps
- O’Donnell/Niall/McLennon (Porsche) - 26 laps
- Alford/Leemhuis/Beechey (Porsche) - 33 laps
- Pye/Barbour/Pither (Holden) - 39 laps
- Thomlinson/Dippie/Maddren (Porsche) - 42 laps
- Thomson/Klien/Harley (Lotus) - 43 laps
- Newman/Lillie/Atkinson (Holden) - 48 laps