Ford F-Series sales rose 10.3% in 2012 to 645,316 units, which is 227,004 units ahead of the closest competitor. F-Series has been the best-selling vehicle in the U.S. for three decades. It is worth noting, however, that sales of the GMC Sierra totaled 157,185. Combined sales of the two GM trucks, Sierra and Silverado, totaled 644,906 units. On the GM December sales call, Kurt McNeil, vice president of U.S. sales operations, noted that in December combined sales for the two GM trucks "gave us truck leadership for the month." Sierra and Silverado December sales totaled 69,409, compared with 68,787 for F-Series, which had its best month since August 2007. "Ford can once again hold up the F-Series as the best-selling truck in 2012, but its dominance slowed noticeably by the end of the year," said Edmunds.com analyst Michelle Krebs, in a prepared statement. "F-Series sales were virtually flat in December, and Ford's truck sales overall were down more than 7 percent. Stronger competition from Chevy and Ram is making Ford look a little less invincible these days." Ford is good at fixing problems, but can it fix this one? The automaker is expected to reveal the 2015 F-150 at the Detroit Auto Show, perhaps stealing a bit of the auto industry's attention from the new Silverado. At an investor conference in November, Chief Operating Officer Mark Fields was coy regarding the question of whether Ford will bring out a new F-150. "We take leadership very seriously," he said. "We also know that as a leader you have a target on your back. That's what drives our product planning going forward." Follow @tedreednc-- Written by Ted Reed in Charlotte, N.C.