The 59-year-old, one of the last senior executives from the tumultuous Jacques Nasser era, started as Ford's vice president of design in 1997 after working with BMW, Audi and Volkswagen.
His design work shaped the 2014 Ford Fusion/Mondeo, the 2012 Ford Focus and the 2011 Fiesta. But he was also responsible for much of the styling of the 2008 Jaguar XF, 2010 Ford Mustang, the current F-150 and the 2005 Ford GT.
J ("just J, that's my name", he said at one launch in Detroit) Mays also led development of a concept cars including the Ford Interceptor, Fairlane, Shelby GR-1 and 427, Jaguar F-Type and the 2012 Lincoln MKZ Concept.
But his career was not without controversy. He was criticised for delivering the "bland" Ford Five Hundred and Freestyle but, in a 2012 interview with Automotive News, he acknowledged: "I don't want to push this onto somebody else".
"I don't think the Five Hundred or Freestyle was one of my brighter moments in Ford, but designing a car is not a solo effort and a lot of people have input on the kind of product they want," he said.
"I've been at the company 13 years and I've been through five CEOs. Some of those CEOs have had more conservative tastes than others. And thankfully the one we have now lets me swing for the fences." Mays was seen to redeem himself under current Ford CEO Alan Mulally, notably with the Ford Fusion/Mondeo and the Fiesta.
He will be replaced on January 1, 2014 by Moray Callum (54), the current design director for Ford in North America.
The writer is on Twitter: @cg_dowling