Forget the Ford GT; Moray Callum's biggest hit is the aluminum F-150

It's tempting to anoint the current Ford GT supercar as Moray Callum's greatest hit while head of Ford design. That car sucked the oxygen out of Detroit's Cobo Center that cold day in January 2015 at the North American International Auto Show when Ford pulled the covers off the fastest production car it has ever built.

I can still recall the look of ashen-faced Honda executives as busy reporters walked right past the brand-new Acura NSX, rushed to the Ford stand 50 yards away and craned their necks for a peek at Ford's V-6 turbocharged road rocket. The crowd never let up for the entire show, and you couldn't put a dollar figure on the global publicity Ford garnered for the GT, which went into production the following year.

For Callum, 62, who said Monday that he's retiring May 1, the GT was a triumph to be sure. But inside Ford, executives are very likely going to look right past the GT and tap another Callum triumph as far more important than the low-volume supercar. We're talking, of course, about the vehicle that pays all the bills at Ford, the F-150 pickup.

Ford took one of the biggest gambles in its recent history when it transitioned the cash cow from steel to aluminum in the fall of 2014. Most people focus more on the myriad manufacturing challenges of that maneuver. But the 2015 F-150's design was also extremely crucial to its success. Aluminum body panels back then were not as malleable as the steel panels used on every Ford truck since the Model T. Callum's designers had far less freedom to design curves and accent lines and many of the small touches that give a vehicle character.

It's true that the 2015 F-150 is flatter and far more squared off than the steel-bodied 2014 model. And you can see that especially in the fender flares, which shrunk considerably on the 2015 aluminum truck, and the doors, whose accent lines almost disappeared. And yet the F-150 made a seamless transition from 2014 to 2015. Sales not only increased, but so did the truck's average transaction price, says Ford spokesman Mike Levine. Ford does not break out sales of the individual F-Series models.

Looking beyond the F-150, Callum deftly played his hand with Lincoln's rebirth. Although Lincoln was not going to get its own unique vehicle architectures separate from Ford vehicles, Callum knew that he could still write a compelling story for Ford's luxury brand. He did that by giving Lincoln's interiors a handcrafted look and using expensive materials in the key areas that customers touch. The Lincoln Aviator and Navigator built on the success of the reborn Continental.

Callum will never be able to outrun the GT; no doubt he'll be answering questions about it as long as he lives. But chances are, Callum will tell you that managing the team that kept the F-Series atop the sales chart is his greatest hit.