The brief

  • What happened: IMSA’s entry list for the Sahlen’s Six Hours of the Glen on June 28 runs to a near-capacity 54 cars across all four classes for the first time since Sebring: 11 GTP, 11 LMP2, 12 GTD Pro and 20 GTD. The race is Round 6 for GTP, Round 3 for LMP2 — which resumes its season here — and Round 5 for both GTD categories.
  • Why it matters: A full, four-class grid at a marquee endurance round signals healthy participation, and the six-hour format is the third of five Michelin Endurance Cup races, so points carry extra weight. The depth is real even as questions swirl above it about how long the GTP class stays this strong.
  • What to watch: Acura confirmed it will pause its factory GTP program after 2026, leaving Aston Martin, BMW, Cadillac and Porsche as the expected core for next year. How the remaining manufacturers and a fresh Balance of Performance shake out at the Glen is the subplot worth tracking.

Fast context

RACER’s entry breakdown notes the field is near capacity with all four classes present, and IMSA’s own entry-list notebook confirms the class split and LMP2’s return after the category sat out recent rounds. Endurance-specific lineup changes are in play, including tweaks at Sebring GT-class winners Manthey and AF Corse USA.

Balance of Performance is the technical story underneath the entry count. Sportscar365 reports that all of Porsche’s 963 specifications received positive BoP adjustments for the Glen — a meaningful swing in a class that has often run close on outright pace.

The longer-term worry sits at the top of the chart. After Acura confirmed it will pause its GTP effort at the end of the year, the remaining manufacturers have publicly backed the category while acknowledging it needs to be stronger. An 11-car GTP entry this weekend is a reminder the present is healthier than the headlines suggest.

What changes next

The six hours themselves are the immediate test: tire strategy and traffic management through a packed 54-car field decide the Michelin Endurance Cup points. Beyond the Glen, watch whether the BoP move tightens the GTP fight at the front and how the manufacturers staying past 2026 position themselves as Acura winds down.