Bourdais and Renger van der Zande currently sit sixth in the standings with two races to go, having scored a single victory in their #01 Chip Ganassi Racing Cadillac V-Series.R at Laguna Seca in May.
The Frenchman noted that the change in tyre compounds that began three races ago at Watkins Glen had adversely impacted Cadillac's form, having finished no higher than fourth since the six-hour race.
