Brad Keselowski became Penske's first NASCAR Sprint Cup champion even before the finish of the 2012 season finale at Homestead after rival Jimmie Johnson hit trouble.
Johnson had managed to move into the race lead as he attempted to pull off an alternative pit strategy.
But at what would have been his final pit stop, a missing lug nut caused a delay and a subsequent penalty. Shortly afterward, Johnson retired to the Hendrick garage area with an apparent transmission problem.
With Johnson needed to overturn a 20-point disadvantage to Keselowski in the standings, it soon became mathematically impossible for the five-time champion to take the 2012 title.
Kyle Busch is leading the race into the closing laps. Keselowski has run around the lower part of the top 10 for most of the day.