An interesting story is told each year through numbers amassed inside the paddock for IMSA’s Rolex 24 At Daytona.
As the entry list is assembled for January’s big season-opener at Daytona International Speedway, the final figures for each class are received by IMSA CEO Ed Bennett and his colleagues like grades on a report card that are made public and can’t be ignored.
It’s an annual process that comes with anxiety and hope as the answers for the overall grid size, and the individual breakdowns in each prototype and GT category, feel like a performance review delivered by the auto industry, and IMSA’s team owners, who tell the series – with their participation or absence – if they believe the WeatherTech SportsCar Championship is on the right path.
Once known for its robust grids, the decade’s first Rolex 24 was a concerning affair as the 2020 edition of the race was down to just 38 cars. Across its four classes, the marquee DPi category – forerunner to GTP – had eight entries, and its pro-am LMP2 ranks put five cars into the field for 13 combined prototypes.
GTLM, known today as GTD Pro after the switch was made from GTE regulations to GT3-based cars, was comprised of seven entries in 2020, and GTD, which was already under GT3 rules, was the largest contributor to the race with 18 entries, giving the GT machines a 25-car footprint.
The 38 from 2020 became 49 in 2021, a 28.9 percent year over year improvement, and by 2022, a 60.5 percent grid expansion with 61 entries was registered. It held at 61 for 2023 before a brief dip to 59 in 2024 was done to make space on pit lane for filming of F1 The Movie, and went back up to 61 – peak capacity for the Rolex 24 – in 2025 as GTP (12) and LMP2 (12) accounted for 24 cars, which was an 84.6-percent leap from 2020.
GTD Pro (15) and GTD (22) delivered 37 entries, nearly matching the entire 38-car field from the start of the decade. The next running of the race across Jan. 24-25 will feature another full grid of 61 entries, giving IMSA a fourth consecutive Daytona curtain raiser that’s at maximum subscription.
“We had some grids in the start of the new IMSA era in 2014 that were really big, and then it started to taper off as it went from 60s to 50s to 40s and then the high 30s,” Bennett told RACER.
“And now we’ve had this trend for the last many years of being just completely full to capacity, and you’ve got people on a waitlist. If you could make it perfect, it’d be 50 percent prototype, 50 percent GT. It’s not the way it always shakes out, but it doesn’t get terribly far from that.”
IMSA crafted its own prototype formula in 2017 with DPi, which used LMP2-based cars fitted with custom engines and bodywork supplied by car manufacturers. The Daytona Prototype internationals launched with four brands as Acura, Cadillac, Mazda, and Nissan went into battle, but the Nissan factory effort enlisted by a privateer team was done after one season and Mazda followed at the conclusion of 2021, leaving Acura and Cadillac to fight amongst themselves in 2022 as the hybrid GTP formula was being readied.
DPis weren’t welcome in the FIA WEC, and specifically, at the ACO’s 24 Hours of Le Mans, which stunted DPi’s growth for all but the manufacturers that were primarily focused on prototype racing in North America.
Then came GTP – effectively DPi 2.0 – where IMSA worked with the FIA and ACO to integrate the concept into a new rules package alongside the FIA’s LMH formula, which created two options for manufacturers to choose from starting in 2023.
DPi was down to a two-badge show for its final year in 2022, but the move to GTP and global alignment of top-level prototype rules has stoked new manufacturer interest. Richard Dole/IMSA
Holding fast to the LMP2-based roots of DPi, but with new hybrid powertrains and greater freedom for manufacturers to customize their bodywork, has been a game-changer for IMSA. The LMDh rules it uses in GTP, which the FIA WEC also utilizes in its Hypercar class, have brought nine car companies into the frame for global and domestic competition.
Five manufacturers competed in GTP through 2025, which drops to four in 2026 after Lamborghini’s global pause to its LMDh program, but growth is on the way with Hyundai’s Genesis marque next year in the WEC, plus Ford and McLaren are preparing WEC programs for 2027; all three have chosen LMDh as their platforms. There’s an expectation for GTP to gain one or more of those brands by the end of the decade.
Prior to IMSA’s shift from DPi to GTP, Bennett and series president John Doonan addressed another shortcoming with its Rolex 24 entry list in GTLM.
A shortfall of six total GTLM cars representing four manufacturers in 2021 was replaced by a doubling in 2022 with 13 cars and seven brands, a byproduct of embracing GT3 for both GT classes. The FIA WEC followed the switch from GTLM to GT3 in 2024.
Bennett credits the sustained spike in Rolex 24 entries, and IMSA’s high car count throughout the season, to its international alignment with the ACO and FIA WEC on GTP/LMDh, GT3, and the ongoing use of LMP2 to drive interest for its championship.
“You have a couple of factors in there,” he said. “When we went to global specifications and started on that journey, we looked back at these historical specifications of our own here for the American Le Mans Series and for Grand-Am, and wanted to respect all those customers’ investments in the different types of specifications that were allowed. It was a lot of colorful ideas that didn’t always mesh together. So we asked ourselves, ‘where are we going? If we had a chance to start with a clean sheet of paper, what should we do?’
“We didn’t want to obsolete any hardware in the short-term as we brought both series together (under one roof as IMSA), so we worked with what we had and they evolved over time, just as our classes evolved over time, and then we got to the point around five years ago when we had opportunities to start looking at global regulations. Manufacturers were really committing to global race cars, asking for more places to bring those global cars.
“We don’t really have any one-off cars anymore. Everything is global in nature, which is a big change in strategy, and that’s something to react to. So for all the GT competitors with GT3 cars, those are now eligible to race just about everywhere. There’s LMP2. And GTP, or LMDh as it’s called in the WEC, plus LMH, which we haven’t had as many of, but there’s the eligibility for them to race here with us. So you look at the 18 manufacturers that have invested in IMSA, and each one is here with a global car, the global specifications. Taking that approach is what’s gotten us to where we are in this moment.”
For Doonan, who was recruited from Mazda by IMSA chairman Jim France and presided over his first Rolex 24 with the unflattering 38-car grid, the rebound started with farewelling the amazing but shrinking GTLM category.
“I remember exactly where I was standing when Ed and I had the conversation about GTLM coming up on the end of its homologation,” Doonan said. “We decided together, as always, with input from our stakeholders, on going to the GT3 specifications which, based on feedback, many of the manufacturers wanted a GTD Pro and a GTD option, so going to that global specification was a real boost.”
IMSA brought LMP3 cars into the WeatherTech Championships for a few years, which helped to pad the grids, but did little to appease its fans as the third-tier prototypes were responsible for quite a few clashes and cautions. With LMP3 dropped after the 2023 season, LMP2 has been the only pro-am prototype class in IMSA’s headlining series, and thanks to the FIA WEC’s call to eliminate LMP2 from its schedule, barring Le Mans, the category has been revitalized in the U.S.
“Look at LMP2, which with GTD, for me, are right at the heart of what the Bishops and the Frances (IMSA’s founding families) had in mind were,” Doonan continued. “It’s opportunities for people that don’t do racing as their full-time profession. So we had LMP2 grids where we were not sure if we were going to have enough to fill a podium, and now we’ve gone from barely making a podium to going over a dozen this year.
“And I’ll echo what Ed said about the reasons why. When we made the transition to globally homologated cars, it created a sense of stability. The longer the runway that we have been fortunate enough to give to teams, to manufacturers, to drivers, to corporate partners, to track promoters, with cars they’ll have for many years has, I think, brought a stability that makes it easier for everyone to plan and invest from. They have a business model that isn’t going to be changing all the time as chassis rules come and go. I think it’s just creating a consistent momentum, and that’s why I think you’re seeing the at-capacity grids.”
IMSA’s CEO says he draws inspiration from the name of the company when it’s time to consider making significant changes to its course.
“The acronym, International Motor Sports Association, we take the last word very seriously,” Bennett said. “IMSA’s an association. We serve at the pleasure of our members, so we better talk to them a lot, we better make sure they have a voice. We better take their wishes and desires of what direction we should go and how to improve things. The best decisions we make are when we’re working closely with our members and partners.
“And inside the company. It’s become such a unique friendship and partnership for me with John (Doonan). We’re like the yin and yang. John’s the face, he knows everybody, he’s out there every day. And I try to think like, ‘Okay, how can we work together as teammates and partners and have different roles?’ We try not to trip over each other, so we talk all day. He’s usually the first person I talk to, and usually the last from a business standpoint at the end of the day. It’s 10 times per day or more, sometimes, even in the car on the drive home, because anytime we learn something, or have an idea, we just want to share. It’s been special.”