On-track action at the Chevrolet Detroit Grand Prix kicked off with the first IMSA WeatherTech SportsCar Championship free practice session of the day, with GM cars leading both classes in the first 90-minute session.

The two Porsche Penske Motorsport 963s still lead the 64th Rolex 24 At Daytona after two hours of racing, while the Corvette Racing by Pratt Miller Motorsports Z06 GT3.Rs have traded places at the head of the GTD Pro field.