2018 Chevrolet Sports Car Classic

[2] On May 25, 2018, IMSA released the latest technical bulletin outlining Balance of performance for the GTD class.

Robby Foley joined Bill Auberlen in the Turner Motorsport entry while Mario Farnbacher substituted for Álvaro Parente in the Meyer Shank Racing No.

86 entry due to a clash with the Blancpain GT Series Endurance Cup round at Circuit Paul Ricard.

[7] Jeff Segal substituted for Alessandro Balzan in the Scuderia Corsa entry due to a medical procedure.

[9] The first practice session took place at 8:15 am ET on Friday and ended with Ricky Taylor topping the charts for Acura Team Penske, with a lap time of 1:21.909.

[10] The second and final practice session took place at 1:05 pm ET on Friday and ended with Hélio Castroneves topping the charts for Acura Team Penske, with a lap time of 1:22.363.

[9] Both categories had 15-minute individual sessions, and regulations stipulated teams to nominate a single driver to qualify their cars.

The competitors' fastest lap times determined the starting order with the grid arranged to put the Prototype cars ahead of all GTD entries.