The 47-year-old actor has been racing for over eight years and competed in his second 24 Hours of Le Mans in France this year, racing a Porsche 911 GTS RSR and finishing fourth in his class.
'Grey's Anatomy' star Dempsey has loved motor racing since he was a young boy but it was his spouse Jillian Fink who convinced him to actually compete.
During an appearance on 'The Late Show with David Letterman', he revealed: "I've loved it since I was a kid and always loved it. My father was very much into it. The Indianapolis 500 was a big event in our house and that's how it started. I watched a lot of television and my wife got tired of me sitting around, so she said, 'Get off the couch and go learn how to.' "
Dempsey's trials and tribulations in the 24-hour pro-am endurance race this year have been chronicled for a four-part TV documentary series, 'Patrick Dempsey: Racing Le Mans', and it will also explore the relationship between Hollywood and racing.
The actor explained: "It's a four parter and the first part is setting up Le Mans, what it means and the history. Also Paul Newman, Steve McQueen and James Garner are big racers. Paul Newman had raced there and was on the podium, and an incredible racer, Steve McQueen of course did the movie 'Le Mans' and Garner was a big off-road racer."