The list of legendary actors-turned-racers is as short as it is iconic: Paul Newman, Steve McQueen and James Garner. Patrick Dempsey became the latest to join this elite group when he tackled the world’s oldest — and most grueling — automotive endurance race, France’s 24 Hours of Le Mans.

“Racing is my true passion, and taking on Le Mans is the biggest challenge of my life so far,” says Dempsey, the actor with nearly 40 film credits who’s most commonly known as Dr. Derek “McDreamy” Shepherd on Grey’s Anatomy. Arriving in Le Mans, France for the race was a thrilling, but nerve-wracking, experience for Dempsey. “It was just nice to get back in the car after being there for a few days,” he said post-race. “I love all the activities that are around the track leading into the race but nothing much has to do with actually being in the car. Once you drive, that gets rid of some of the jitters, some of the nervousness and you can just settle in.”

Discovery Communications captured Dempsey's knuckle-biting experience on film to create "Patrick Dempsey: Racing Le Mans," a world-premiere television event debuting on Velocity on Wednesday, August 28 at 10 p.m. ET/PT. “Patrick Dempsey: Racing Le Mans” follows Dempsey as he and his team, co-owned with Italian soccer superstar Alessandro Del Piero, prepare for the vehicular equivalent of climbing Mt. Everest. From sponsor recruitment to time trials, to juggling his family and Hollywood career, the four-part miniseries includes an all-access account of Team Dempsey as they prepare to risk everything on Europe’s most historic track.

“Just getting to Le Mans is almost as challenging as the race itself,” says Dempsey, who has competed in auto racing for several years while maintaining a TV and film production schedule for such recent features as Transformers: Dark of the Moon and Flypaper. “This project reflects a 360-degree view of the entire race process, including all the ups and downs along the way.”

Dempsey, who owns an exclusive sports and vintage car collection, previously 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. Dempsey 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 (with Dempsey himself driving) from Laguna Seca onward. After debuting at the 2009 24 Hours of Le Mans, Dempsey returned to France four years later to compete in a Porsche 911 GT3 RSR at the 2013 24 Hours of Le Mans endurance race.

Spoiler: At the end of 305 laps, Dempsey and his co-drivers, Joe Foster and Patrick Long, finished 29th overall and fourth in-class.

“We were competitive the entire race,” says Dempsey, who led the race twice during his second driving shift. “This is really what you want to be. Patrick did a great job on his opening stint, Joe was incredible in what seemed like every session of his in the rain, and our Porsche from Proton Competition was perfectly prepared. It was just a great race.”