The first use of what would become Le Mans Prototypes was at the 1992 24 Hours of Le Mans. In an attempt to increase the number of entrants, older Porsche 962s were allowed entry in Category 3, alongside small open-cockpit race cars using production road car engines in Category 4. Later, the ACO announced its intentions to completely replace Group C cars with Le Mans Prototypes, creating two classes: LMP1s with large displacement custom-built engines, and LMP2s with smaller displacement production-based engines. Both classes were required to have open cockpits.
The 1997 saw the launch of the first European series based around Le Mans Prototypes, known as the "International Sports Racing Series," using classes similar to LMP1/WSC and LMP2, referred to as “SR1” and “SR2” by the FIA. In 1998, the United States Road Racing Championship attempted to break away from the IMSA GT Championship, naming their open-cockpit prototypes “Can-Am.” The American Le Mans Series was created following the cancellation of the IMSA GT Championship at the end of 1998, using the same class structure as the 24 Hours of Le Mans and becoming the first championship to use the LMP name. The ACO altered their LMP classes in 1998, briefly eliminating the smaller LMP2 class and allowing a new class of closed-cockpit prototypes, known as “LMGTP.”
The LMP1 category was retired at the end of the 2020 season and replaced by the Le Mans Hypercar class.
From 2017, FIA introduced new regulations for LMP2, locked in through 2027, aiming for a significant power increase and a four-second decrease in lap time at Le Mans. Gibson Technology is the exclusive engine supplier, producing a 4.2-litre naturally-aspirated V8. In seasons 2017 through 2020, the engine produced about 600 bhp. Dallara, Onroak Automotive (Ligier), Oreca and Riley Tech/Multimatic were selected as the exclusive chassis constructors, requiring closed-cockpit designs.
Before the 2021 season, LMP2 cars were slowed down to ensure a lap time difference between LMP2 and the Le Mans Hypercar class. The power of the Gibson engine was reduced to 560 bhp, and then further to 540 bhp, with the minimum weight increased to 950 kg. A single aero kit was made mandatory across the season, limited to the Le Mans specification in the WEC. Oreca and Ligier were chosen as constructors for the 2028 regulations, with Gibson continuing to supply the engines.
LMP3 is an entry-level prototype class intended for introducing young drivers and new teams to endurance racing. LMP3 uses closed-cockpit chassis, which can be built by any licensed constructor, with costs capped for the chassis, engine, and generational upgrade kits.
Cars eligible for the 2015–2019 first-generation ruleset included the Ginetta-Juno P3, Ligier JS P3, Norma M30, ADESS-03, and the Ave-Riley AR-2, powered by a 5.0-litre Nissan VK50 V8 engine producing 420 hp. The minimum weight was originally 900 kilograms, before being increased to 930 kilograms.
A second generation ruleset was introduced for 2020, with new cars including the Ginetta G61-LT-P3, Ligier JS P320, Duqueine D-08, and the ADESS-03 Evo. Engines were upgraded to the 5.6-litre Nissan VK56, increasing horsepower to 455 hp.
From 2025, the engine used in the class is the twin-turbocharged 3.5-litre Toyota V35A, bringing about a power increase to 470 hp. The weight limit was increased to 1,000 kilograms, necessitating a crash test. New cars introduced included the Ginetta G61-LT-P3 Evo, Ligier JS P325, Duqueine D09, and the ADESS AD25.
LMPC (Le Mans Prototype Challenge) was an earlier entry level class, introduced in 2009, consisting of competitors running identical Oreca FLM09 cars. The class was dropped in European Le Mans Series in 2014 and after the 2017 season in the WeatherTech SportsCar Championship, as the cost of running an LMPC team was found to be comparable to that for an LMP2 team.
Le Mans Prototypes have used various names depending on the series in which they compete. The FIA’s equivalent cars were referred to as Sports Racers (SR) or Sports Racing Prototypes (SRP). The American IMSA GT Championship termed their cars World Sports Cars (WSC), while the short-lived United States Road Racing Championship (USRRC) used the classic Can-Am (CA) name for their prototypes. Since 2004, most series have switched to referring to these cars as Le Mans Prototypes. The American Le Mans Series officially referred to the cars simply as Prototypes (P1, P2, or PC). An LMP is commonly referred to as a Le Mans car in the media.
Daytona Prototype – Prototype racing car Daytona Prototype International (DPi) Formula Le Mans – Sportscar racing class Group 6 – FIA classification for sports car racing Japan Le Mans Challenge