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.
“We can see that some cars use the tyres better than others depending on the conditions,” Bourdais said.
“We’ve been using the harder tyre from Michelin ever since Watkins Glen and it’s definitely flipped the order a little bit.
“The Cadillacs were a bit happier on softer compounds, taking better care of the tyres.
“Now that it’s the harder tyre through the summer and it’s going to hold true at Indy, it has been harder for us to extract the most out of it and others have been able to kind of pop up in terms of performance.
“It’s interesting to see the evolution track to track and circumstances after another. I think it’s all very close.
“The BoP [Balance of Performance] has worked well. It’s been good racing and we’ve seen a lot of different winners.”
Bourdais noted that the differing nature of the new-for-2023 hybrid GTP cars compared to their DPi predecessors meant everybody was still “figuring things out along the way”.
“For us, the GTP has been quite different because it’s a heavier car with better tyres but more weight with a lot less downforce, so it’s a different combination and you have to be more patient with the car but you still have to push really hard,” he added.
IMSA will return to racing on the Indianapolis road course for the first time since 2015 next weekend, and Bourdais explained that a test conducted recently by Ganassi yielded improvements for the most recent round at Road America.
“It was good to go testing [at IMS]; it was really the first test to prepare for Indy since Sebring,” he said.
“So, we learned quite a bit of things about the car, and we went to Road America and it was definitely beneficial. We were on pace and happier right away.
“The race weekend didn’t necessarily turn out the way we wanted, but it definitely felt like we found a step in terms of pace. It’s a classification that changes a lot.”
