Following the FIA World Endurance Championship’s transition to a winter calendar in 2018, IMSA announced in January 2018, that it would extend the homologation periods for LMP2, DPi and GTE-spec machinery in the WeatherTech SportsCar Championship by an additional year. “This would delay the homologation periods in the championship by roughly six months, which necessitated the homologation extension from IMSA.” The extension meant DPi and LMP2 cars would be eligible for competition until at least the end of the 2021 season. Despite calls from manufacturers to retain the DPi platform and regulations for the 2022 season, then-IMSA President Scott Atherton announced that IMSA was looking at other options beyond a further extension to the life of the DPi platform.
On May 6, 2019, IMSA announced that the next generation DPi ruleset, known as DPi 2.0, would be an evolution based on the current LMP2-based platform, featuring hybrid technology from a single supplier. A few days later, IMSA's VP of Competition Simon Hodgson stated that the next-generation DPi regulations would be expected to feature increased styling measures, by opening up more areas where manufacturers were able to add styling cues. Hodgson also indicated that the enlarged scope for styling cues may also come alongside regulations that dictated a minimum level of styling required from each manufacturer.
On June 24, 2019, it was revealed that IMSA had held discussions with manufacturers regarding the incorporation of hybrid technology in the next-generation DPi ruleset, with manufacturers on the DPi 2.0 steering committee divided over the level electrification in the hybrid systems. Electrification concepts proposed included high and low-voltage systems of varying costs. A further meeting held in late June saw a 400-volt system, providing in the range of 70-90 kW (90-120 hp) of electric power emerge as the leading electrification option. However, despite 400-volt systems having emerged as the leading option in June, it was revealed in September that discussions had yet to reach any form of consensus, although it was agreed that manufacturers could build their own hybrid systems.
Following the 2019 “Super Sebring” weekend which saw the 2019 12 Hours of Sebring held on the same weekend as the inaugural 1000 Miles of Sebring, WEC CEO Gerard Neveu revealed the possibility of DPi becoming included as part of the “Hypercar” regulations, with the integration of DPis depending on the performance levels of both platforms. “On July 31, 2019, Neveu revealed that an active effort was underway between the ACO and IMSA technical departments to seek similar performance targets between Hypercar and DPi 2.0, which would allow for both platforms to eventually crossover and compete head to head.”
Toyota stated in November 2019 it would be open to DPi integration into the FIA World Endurance Championship's top class, on the condition it would not hinder the display of its hybrid technology. McLaren announced it would not be considering a LMH programme, and instead called for DPi to be brought into the WEC, with McLaren Racing CEO Zak Brown stating that a LMH programme was unviable for the British manufacturer. Ford and Porsche expressed similar sentiments, calling for convergence between LMH and DPi.
On January 24, 2020, a joint ACO and IMSA press conference announced Le Mans Daytona h (LMDh), a set of regulations intended to supersede the existing Daytona Prototype International (DPi) cars. “LMDh was to be converged with the incoming Le Mans Hypercar regulations, allowing both LMH and LMDh entries to compete in the top class in both the WEC and IMSA’s premier series.” Initial plans to allow manufacturers to build their own hybrid systems were scrapped in favour of a spec 50 kW (67 hp) hybrid system.
The draft regulations specified a car weight of 1,030 kg (2,270 lb), a peak combined power of 500 kW (670 hp) from engine and hybrid system, a single bodywork package, a single tyre supplier, and a global Balance of Performance system to balance LMDh and LMH cars. The gearbox hybrid system will be supplied by Xtrac with an integrated motor generator unit supplied by Bosch and batteries from Williams Advanced Engineering. Chassis suppliers include Dallara, Ligier, Multimatic, and Oreca.
In January 2022, IMSA confirmed the name for the class would be GTP, referencing the 1980s category of the same name. The class debuted in IMSA at the 2023 24 Hours of Daytona with four different manufacturers entering a total of nine cars. LMDh entries comprised the entirety of the class in 2023 and 2024, only racing alongside an LMH entry for the first time with the introduction of the Aston Martin Valkyrie AMR-LMH for the 12 Hours of Sebring in 2025.
The World Endurance Championship introduced their equivalent to GTP in 2021, known simply as Hypercar, and LMDh cars began competing in the series in 2023. In 2025, the Hypercar class was announced to be allowed to participate in the Asian Le Mans Series with customer teams and Pro/Am lineups, meaning LMDh vehicles would be eligible to compete in the AsLMS starting from the 2026/27 season.
This article is based solely on the supplied corpus: a single Wikipedia article on LMDh. No external sources, such as primary archives, autobiographies, period programmes, or specialist publications, were consulted.