Michael Shank Racing pulled off a Riley during the final stint.
Allmendinger shared driving duties with Grand Am Rolex Sports Car Series regulars Ozz Negri and John Pew, as well as IndyCar Series driver Justin Wilson in the 50th anniversary of the 24-hour endurance race at Daytona International Speedway. The 30-year-old Allmendinger crossed the finish line 5.2 seconds ahead of Starworks Motorsports' No.8 Ford-Riley, which was driven by Ryan Dalziel during the last hours of the event.
With a little more than one hour to go, Allmendinger put the No.60 car in the lead for good. However, Allmendinger had to swerve wide in turn one to avoid hitting a GT car during the closing laps. He went at least 20 feet off surface onto the paved skid pad.
"I'm so worn out," Allmendinger said in Daytona's victory lane. "We wanted to win this for Shank. The motor was so fast. I am so drained.
"I knew those last three hours I was going to have to go flat out. It was fun. When Dalziel got in the car...I knew I was going to have to drive my (rear end) off. I pushed really hard to build up a gap and take those last 10 laps to manage that gap."
It's the first time in nine attempts that team owner Michael Shank has claimed the victory in one of the world's most prestigious sports car races. The No.60 team completed 761 laps around the 3.560-mile Daytona road course for a total of 2,709 miles. It was one lap shy of tying the event's all time record, set in 1962.
"I feel like we deserved [a win], to be honest, because we've worked hard, and I don't make any excuses for that, and we've paid our dues for sure," Shank said. "I hope it can take us to new, cool places in Daytona Prototype in the coming years."
Last month, Allmendinger signed with Penske Racing to drive the No.22 car in NASCAR's premier series this season. He drove for Richard Petty's team the past three years. Allmendinger has yet to win a race in any one of NASCAR's three national touring series (Sprint Cup, Nationwide and Camping World Truck).
"I look at this year as being my best opportunity to win a Cup race, but that's easier said than done," he said. "Right now, I'm just going to take this for what it's worth and not think about anything for a couple of days and enjoy it. Right now, it's the biggest win I've ever had, because we've worked for seven years to get to this point with Mike Shank, and we've been so close so many times."
Wilson competed for the first time since last August when he suffered a back injury during a practice crash at Mid-Ohio Sports Car Course, which curtailed his 2011 IndyCar season.
"We all managed to comprise enough to get by between all four of us in being comfortable and being able to push the limit every single lap, because this was a tough race," Wilson said.
Dalziel partnered with Allan McNish, Alex Popow, Enzo Potolicchio and Lucas Luhr in the No.8 car.
Brazilian Felipe Nasr finished third in a second Shank car, the No.6 Ford- Riley.
NASCAR driver Juan Pablo Montoya finished fourth overall -- one lap down -- in the No.02 Chip Ganassi Racing BMW-Riley. It's the first time since 2005 that a Ganassi car was not on the podium for the 24-hour Daytona race. Montoya teamed up with fellow Sprint Cup driver Jamie McMurray and IndyCar champions Dario Franchitti and Scott Dixon.
"It was a great race - an epic 50th Rolex 24," Ganassi said. "My congratulations to Mike Shank and Ford for a fantastic race, but I don't want them to get too comfortable in victory circle."
Defending race and Grand Am champion Scott Pruett finished sixth in Ganassi's No.01 BMW-Riley. A transmission problem that occurred late in the race put Pruett four laps behind.
The GT class victory went to Andy Lally, John Potter, Richard Lietz and Rene Rast in the No.44 Magnus Racing Porsche. The team finished 11th overall in the race.
Lally has returned to Grand Am after capturing the rookie-of-the-year title in Sprint Cup last year.
"I absolutely knew we had the potential to do it," Lally said. "It was a pleasure to be able to join the team. It was absolutely epic to come home."