As the IMSA and Grand-Am merger was announced on September 5, 2012, between NASCAR Holdings (Grand-Am's owner) and Panoz Motorsports, the 2013 season was the transition season as both series were now held under the NASCAR Holdings banner.
At the seventh round in Baltimore, Muscle Milk Pickett Racing successfully defended their 2012 Prototype One championship.
However, with this date conflicting with the 24 Hours Nürburgring, the series opted to move the event up one week to May 11.
Points were awarded to the top ten cars and drivers which complete at least 70% of their class winner's distance.
Drivers are required to complete a particular amount of the minimum number of laps in order to earn points.