The victory at the Michigan International Speedway snapped a 76-race winless streak for Earnhardt, who had not won a race since May 2006 at Richmond, Va.
His No. 88 Hendrick Motorsports Chevrolet was running on fumes when it coasted across the finish line Sunday ahead of runner-up Kasey Kahne and third-place finisher Matt Kenseth. Brian Vickers finished fourth.
In the end, the race was decided by which driver had the best fuel-conservation strategy.
"I didn't think we had enough fuel when the caution (flag) came out," said Earnhardt. "We had it set up for the win if we didn't have a caution."
The caution flag was necessary because Sam Hornish Jr., driving the No. 77 Dodge, spun out on lap 198 despite a pit stop for a right-side tire change.