JDC-Miller Motorsports has discontinued its Prototype Challenge program, adding to a further depleted grid in the spec prototype class, with only one full-season entry currently confirmed in the category’s final year in the IMSA WeatherTech SportsCar Championship.

The Minnesota-based squad, which had initial plans of continuing in PC alongside its new Oreca 07 LMP2 effort, has elected to focus on the new full-season Prototype entry instead, according to team co-owner John Church.

Church told Sportscar365 that driver lineup for the Oreca 07 will be announced this week. The team tested four drivers, including Mathias Beche, in a multi-day test at Sebring last week.

The termination of JDC-Miller’s PC program is the latest in an increasing list of teams not returning to the class next year.

Five-time class champions CORE autosport has moved to GT Daytona with a new Porsche 911 GT3 R, while Tequila Patron North American Endurance Cup champions PR1/Mathiasen Motorsports has purchased a Ligier JS P217 for its step up to the P class next year.

Reigning class champions Starworks Motorsport has yet to confirm a full-season entry, with Peter Baron admitting that the Florida-based team could instead focus on a two-car Patron Endurance Cup program-only.

Starworks fielded as many as three cars in select races last year. “It’s not the world’s best year for selling a PC program,” Baron told Sportscar365.

Series stalwarts Performance Tech, could be left in a similar position, with the Brent O’Neill-led operation yet to finalize its return, although O’Neill said he’s hopeful of getting a program into place later this week.

The only confirmed full-season entry, so far, is BAR1 Motorsports, with team principal Brian Alder telling Sportscar365 that he has a pair of drivers committed for the year and is currently working on a second season-long effort.

Alder said that both of the cars will be at Daytona, which is likely to see a 4-5 car PC class entry, but drop off as the season unfolds.

The class has an eight-round schedule next year, including all four Patron Endurance Cup races, plus the races at Circuit of The Americas, Detroit, Canadian Tire Motorsport Park and Road America.