Both Daytona Prototypes and Prototype Challenge cars are closing on the projected end of their lifespans at the end of the 2016 TUDOR United SportsCar Championship season.

In April, IMSA announced that it and the ACO will use the same technical regulations and share the same Prototype race car constructors, and IMSA’s position with regard to the top prototype class has not changed beyond that point.

However, per sources to Sportscar365, it may not be 100 percent guaranteed the top Prototype class in IMSA will feature solely the new global LMP2-based prototype as defined by the ACO and FIA.

According to IMSA President and COO Scott Atherton, all options remain on the table for potential prototype combinations.

The combinations could be a mix of any of the four outlined prototype platforms (DP, P2, P3, PC), but unlikely to feature more than any two.

“At this moment all of those scenarios are possible,” Atherton told Sportscar365. “We haven’t ruled out anything and we made any final decisions.

“We know for sure that our top Prototype category is going to embrace the next generation prototype as of January 2017.

“What surrounds it, if anything, is yet to be determined.”

IMSA is closing on an LMP3 test after the Watkins Glen race in June, as a first step in determining its potential viability for series introduction.

The reason for the prototype class openness, according to Atherton, is the variation in potential new-for-2017 prototype model cars that could be eligible in the TUDOR Championship.

“You’re aware we have agreed with the FIA and ACO that we would limit the number to four [constructors], and we expect there will be many more than that who express an interest,” Atherton said.

“So there’s a decision-making process that will have to be conducted to confirm who those four constructors are.

“We here in IMSA have an added set of criteria because we will be embracing multiple engine configurations as well as have the opportunity, not the requirement, but the opportunity for OEM partners to produce bodywork that evokes a brand connection.

“Having a bespoke body that has design cues/details incorporated into it is another area of complexity that the ACO version of this car will not have.

“We are working in concert with the ACO, with the FIA, so they understand what our expectations are to define the areas of the bodywork, which could be altered, and get that information confirmed and distributed as soon as possible.”

In an interview with Sportscar365, Bentley CEO Wolfgang Durheimer said a Daytona Prototype “could be an interesting subject” for the company.

Atherton said that would come as a surprise to him, and potentially to IMSA.

“I would be surprised that anyone would suggest they’d get into the Daytona Prototype category at this point,” Atherton said.

“We have made it clear that the future Prototype formula for us is in line with the ACO/FIA prototype, what the ACO will be running as an LMP2 and what will be our top prototype.

“So that’s not in line with the current Daytona Prototype specifications. I think somewhere there’s a wire crossed.

“I can’t speak for Mr. Durheimer, but I’d be surprised if that was a serious consideration at this point, knowing that its lifespan right now is relatively brief.”

Atherton said there has been a healthy amount of discussion and dialogue with team owners. Few, if any, owners have committed to their next prototype and almost none have done so publicly as yet.

“There’s a handful of them where they said, ‘We can’t get to 2017 fast enough. Given what we know about the next generation prototype count us in,’ but that’s the exception,” Atherton said.

“Most are saying ‘I need more information before I can give you any feedback or make a decision.’”

Full details of the new 2017 global regulations are expected to be revealed next month during the week of Le Mans.