In 2014, Dempsey told Reuters in the Hockenheimring support paddock at the German Grand Prix that motor racing was not just a hobby, and had become as much a part of who he is as acting. He said, "It's all-consuming in many ways. I couldn't imagine not racing right now. It really keeps me motivated. It's all I think about on a daily basis."
Dempsey, who maintains an extensive sports and vintage car collection, has enjoyed auto racing in his spare time for several years, and declared before the 24 Hours of Le Mans in 2013 that he would like to compete full-time, telling Eurosport:
I would like to make that [motorsports] a complete priority and just focus on this full-time. If I could just walk away from acting, I think I could do that very easily, and just focus on the driving, I would love that more than anything else.
He has competed in prestigious pro-am events such as the 24 Hours of Le Mans, Rolex 24 at Daytona sports car race, and Tecate SCORE Baja 1000 off-road race. He was a co-owner of the Vision Racing IndyCar Series team and current owner of Dempsey Racing, which is presently racing two Porsche 911 GT America's in the Tudor United Sports Car Series . He participated in this series as often as his schedule allowed, although insurance restrictions kept him from driving competitively while also filming a motion picture. In 2009, he raced a Team Seattle Advanced Engineering Ferrari F430 GT in the 2009 24 Hours of Le Mans's GT2 class, and finished ninth in class.
Dempsey announced he would race the 2011 Rolex 24 at Daytona along with other races throughout the season in a Mazda RX-8.
Dempsey finished in third place in the GT Class of the Rolex 24 at Daytona. In 2012, Dempsey competed in the Grand-Am Continental Tire Sports Car Challenge behind the wheel of an Aston Martin Racing-Multimatic Motorsports Aston Martin Vantage GT4, which, after five successful racing seasons in Europe, was to make its debut on American tracks. He formed the Dempsey Racing team to compete in the American Le Mans Series. The team fielded a full-time Oreca FLM09 in the Prototype Challenge class as well as a Lola B12/80 coupe in the Prototype 2 class from Laguna Seca onward.
After debuting at the 2009 24 Hours of Le Mans, Dempsey returned to France four years later and competed in a Porsche 997 GT3 RSR at the 2013 24 Hours of Le Mans endurance race. Dempsey and his co-drivers finished 29th overall and fourth in-class.
Telling Porsche Newsroom: "Not much changes in my TV work, but everything changes constantly in motor racing – every lap, every bend and every moment."
In 2015, Dempsey is focusing on participating in the FIA World Endurance Championship with his own Dempsey Racing-Proton team in the GTE-Am class in a Porsche 997 GT3 RSR, teamed with Patrick Long and Marco Seefried.
You can read more about Patrick's racing career from Wikipedia: