William Clay Ford, who once steered a car from his grandfather Henry Ford’s lap but, overshadowed by his brash older brother Henry II, never got the chance to run the family business, died on Sunday at his home in Grosse Pointe, Mich. Ford’s last surviving grandchild, he was 88.

The cause was pneumonia, the Ford Motor Company said.

Mr. Ford, who was also the longtime owner of the Detroit Lions football team, represented the automaker’s last direct link to the days when the company belonged entirely to the Ford family. He was long the company’s largest shareholder, and the last Ford family member to be a confidant of Henry Ford, the American legend who made the automobile accessible to the masses.

As vice chairman of Ford and the leader of powerful board committees, he provided stability, perspective and stewardship of the family’s interest. Under company bylaws, Ford family members retained 40 percent of voting power, even as their proportion of common stock slipped to less than 2 percent.

Through his marriage to Martha Parke Firestone, granddaughter of the tire magnate Harvey Firestone, Mr. Ford united two of America’s industrial dynasties. Ford has bought millions of Firestone tires.