IMSA And ACO Have Settled On Joint LMDh Class Regulations

Illustration for article titled IMSA And ACO Have Settled On Joint LMDh Class Regulations
Image: IMSA

Back in January the ACO figured out that its upcoming Hypercar class was collapsing like a week-old flan, and had to do something quick. Before the economic disaster that has been the covid-19 crisis, the FIA WEC LMP1 class had already practically dissolved, Hypercar was practically a non-starter, and there would be no exciting new battles at Le Mans for the foreseeable future. Enter IMSA’s second-generation DPI class, which the ACO latched onto like a lamprey as its saving grace. The new “jointly developed” class would be called LMDh.


The class was set to be announced in March at the IMSA/ACO 12 Hours and 1000mi Super Sebring weekend, but that was cancelled thanks to our global viral hellscape. The two parties have been hashing out the details, presumably conducting business over Zoom like the rest of us have been, ever since.

So, here’s what the LMDh class will look like.

The car will be based on the cost-capped and revised LMP2 category chassis, using the same base “spine”, less bodywork and engine. Current LMP2 manufacturers are limited to Oreca, Ligier, Dallara, and Riley/Multimatic, though Ginetta is pushing to be considered for the updated ruleset.

While LMP2 is limited to a common internal combustion engine powertrain, the LMDh class will feature a manufacturer-specific drivetrain. In order to provide extra power over the LMP2 cars, LMDh will share a spec rear-wheel hybrid system. The combined peak power of the hybrid system and ICE in LMDh will be 500 kW.

Where LMP2 cars are currently regulated to 930 kilograms, LMDh will have a minimum weight of 1030 kilograms (2270.76 pounds).

As with current IMSA DPi class regulations, manufacturers will be allowed to build unique and stylized bodywork for their LMDh cars. Teams are not allowed to build multiple bodywork packages for low downforce or high downforce scenarios. Only one bodywork package will be homologated per manufacturer.

All LMDh prototypes will be homologated for a minimum of five years, allowing manufacturers some peace of mind that the investment being made can be amortized across multiple seasons. IMSA and the ACO can’t just change the formula for this class before that five year period is up.


Tires for cars run in either IMSA or ACO competition will be mandated to run a spec Michelin tire.

And perhaps most importantly, there will be a global balance of performance not only across the IMSA and ACO cars, but also across Hypercar classed machines. Toyota, Peugeot, and Glickenhaus have already invested heavily in the LMH class, and would not want to have LMDh given an unfair level of performance in comparison to their much more expensive machinery.


Because the FIA WEC has already voted to move away from a winter series crossing two calendar years starting in 2021, the introduction of LMDh has been pushed out to the start of the 2022 season.

Here’s hoping IMSA and the ACO can work together for the next seven years and this whole thing doesn’t devolve into a pissing match as it usually does when these two get together.

Jalopnik contributor with a love for everything sketchy and eclectic.



Well that both sucks and is cool at the same time.  It essentially means the death of LeMans as we have known it (although I guess you could argue that happened when Porsche pulled out).  Shared chassis with unique bodywork means pretty much no more factory teams, and a serious lack of innovation.  I realize it was necessary for the series to survive, but it still hurts.  Worst part is we still have 2 more years of waiting for it.