Stefan fought back from a lowly starting position to cross the finish line in eighth place in the race at the Mid-Ohio Sports Car Course.

Following an excellent fourth place around the streets of Toronto, Stefan and Walker Racing had to get to grips with another new road circuit. They put in 25 laps in Saturday's 45-minute practice session, making steady progress and finishing 16th on the timesheet.

The afternoon qualifying session began on a damp track and most cars started on wet-weather tyres, but the times set quickly became meaningless as everyone changed to slick tyres. Stefan was in the top five for a brief spell, but as the track dried out the lap times tumbled. Yellow flags shortly before the end of the session ruined what would have been the quickest laps of all, and Stefan finished in 17th place.

Race day was dry and Stefan came an encouraging seventh in the early morning 20-minute warm-up session.

The rolling start of the race was clean and Stefan held his position for the first two laps until he was passed by Richard Philippe making his way through the field after starting at the back. Stefan's car, though, was proving really quick and on lap 9 he overtook Ali Jackson to go 16th. In the next few laps he progressed to 14th following a spin by Charlie Kimball and an off-track excursion by Sebastián Saavedra, and then to 12th as Wade Cunningham collided with Mario Romancini, causing a full-course caution.

By then Stefan had spent a number of laps behind the number 20 car of Ana Beatriz, but not long after the restart following the safety car period he made a decisive overtaking move and claimed 11th place. He quickly pulled away from her and in the next four laps he passed first Mike Potekhen and then Richard Philippe. It took him five more laps to hunt down and overtake Sebastián Saavedra, which put him into eighth place. Over the last part of the race he was hot on the heels of Andrew Prendeville, but the chequered flag fell before he was able to make another passing move.

Stefan's achievement in the race earned him the Hard Charger Award, worth $1,000.