2018 Sports Car Challenge of Mid-Ohio

[1] The race marked IMSA's return to Mid-Ohio Sports Car Course for the first time since 2013 as the track replaced Circuit of the Americas after the 2017 season.

[7] With 95 points, the GTLM Drivers' Championship was led by Ryan Briscoe and Richard Westbrook with a seven-point advantage over Oliver Gavin and Tommy Milner.

[10] In P, Spencer Pigot subbed for Harry Tincknell in the Mazda Team Joest #55 entry due to a clash with the FIA World Endurance Championship round at Spa-Francorchamps.

[11] In GTD, Park Place Motorsports, and Montaplast by Land-Motorsport, CJ Wilson Racing, and Sqaudra Corse Garage Italia were absent.

[17] The first practice session took place at 9:45 am ET on Friday and ended with Ricky Taylor topping the charts for Acura Team Penske, with a lap time of 1:13.601.

[18] The second practice session took place at 3:00 pm ET on Friday and ended with Juan Pablo Montoya topping the charts for Acura Team Penske, with a lap time of 1:36.867.

[20] The third and final practice session took place at 8:35 am ET on Saturday and ended with Dane Cameron topping the charts for Acura Team Penske, with a lap time of 1:12.675.

[17] All three 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 and GTLM cars ahead of all GTD entries.