And it's all thanks to his wife, Jillian.
"Her influence was profound. Jill just gets me to believe in my dreams â€" and act upon them," said Dempsey, who races cars as part of the Hyper Sport racing team.
"She was the one to encourage me to go and drive," he tells the British edition of InStyle about his auto racing passion. "For a Christmas present about nine years ago, she gave me a three-day competition class. Now my goal is to race Le Mans."
Last year, Jillian treated him to a 1969 Mercedes-Benz 280SE for his 40th birthday.
"It's my midlife-crisis car - only there is no crisis," he says.
He also owns the Porsche convertible from the movie Top Gun.
Far from having a midlife crisis, Dempsey, who became the father of twins Darby Galen and Sullivan Patrick on February 1 (he and Jillian also have a 5-year-old daughter, Tallulah) is looking forward to getting older - and even the effect of age on his famous "Dr. McDreamy" hair.
"My hair is a complete nightmare," he tells the magazine.
"The gray is coming in and I'm looking forward to that. I'm going to try and age gracefully and not be neurotic about it."