A brief history of Le Mans prototypes

One of the most complex – and rather confusing (yet impressive) – regulation classes to emerge in modern times has been the Le Mans Prototype (LMP) category as run at Le Mans, and in the American Le Mans Series (ALMS). As its title suggests, this class was conceived largely by the French Automobile Club de l'Ouest (ACO), the jealously-protective and over many decades famously autocratic organisers of the Le Mans 24-Hour race. Their LMP cars have reigned for years now as the fastest closed-wheel competition cars in worldwide road racing.

The Le Mans Prototype class emerged initially at Le Mans in 1992. In that time of austere recession the ACO could see the entry for its 24-Hour race falling under extreme threat. The old and quite successful Group C endurance category had lost support and was in its death throes, partly due to background politicking which concentrated attention – and hard-to-find sponsor support – upon Formula 1. So the ACO opened its legendary 24-Hour race entry to older-style Porsche 962 sports-prototypes, while a new class was also created for small-engined sports-prototypes using production-based power units.

Group C finally died at the end of 1992, so the ACO accepted more production-based cars for its 1993 Le Mans race, while also formally creating its Le Mans Prototype class. Initially the major-category LMP1 cars comprised updated old Group C designs, modified to suit the latest regulations. LMP1s used large-capacity, specialised racing engines – normally with turbocharging – while a supporting LMP2 class was limited to smaller-capacity uprated production engines.

In 1997 the world of prototypes started to get a little confusing. The FIA International Sports Racing Series was launched for Le Mans Prototype-derived cars, organised into SR1 and SR2 divisions based upon LMP1 and LMP2. Meanwhile, in America, the IMSA series of long-distance more-or-less endurance races had been run for many years with considerable success. In 1998 a breakaway series was launched as a new United States Road Racing Championship for which their open-cockpit prototype class took the once-esteemed title 'Can-Am'. This quickly failed, but Rolex stepped in as the rescuing sponsor adopting FIA-like SR1 and SR2 regulations.

The American IMSA GT Championship also went under at the end of 1998, and the American Le Mans Series (ALMS) was created in its place, using the same class structure as had the ACO at Le Mans.

Rather perversely, the great French Club concurrently changed their own LMP regulations, cancelling the smaller LMP2 class, and replacing it with a fresh category for closed-cockpit ‘LMGTP’ (Le Mans Grand Touring Prototype) entries – derivatives of production-based road car designs considered just too advanced and rapid to be truly described as merely GT cars.

Come the millennium and the ACO split its open-cockpit LMP category into two – ‘LMP900’ and ‘LMP675’. The numbers reflected minimum weight limits in kilograms for each class.

The LMP900s were more powerful and faster, the LMP675s smaller, more nimble but somewhat slower in top speed. The ACO intended some parity between the two categories in lap times, while LMGTP continued, supported only by Bentley…

Neither LMP900 nor LMP675 matched either the older SR1 or SR2 classes, so teams competing in the newly renamed FIA Sportscar Championship had to modify their cars to compete at Le Mans and in the new European Le Mans Series (ELMS), which was a new spin-off from the American Le Mans Series.

Are you still with me?

Then there was a struggle – not for the first time – between the overweening FIA and the ACO with its Le Mans 24-Hour race still the most prestigious in the entire calendar. Teams voted with their feet, unwilling to modify their cars to contest ELMS and preferring the single Le Mans race to any rival series with far more obscure qualifying rounds. The FIA Sportscar Championship was duly canceled in 2003. When the American Rolex Sports Car Series replaced its SR classes with their own Daytona Prototypes regulations, the ACO LMPs became the only open-cockpit prototypes left. It was a mess – but the ACO emerged on top.

Their LMP675 class had failed meanwhile to challenge seriously for an outright win. LMGTP had proved too similar to LMP900 – and so the rules were simplified as just LMP1 and LMP2, although the latter became the preserve of private entrants, while major manufacturers were encouraged to contest LMP1. Both LMP1 and LMP2 could use either open or closed-cockpit bodywork. Here was a sensible division of racing categories which was adopted in turn by both the 2004 Le Mans Series and the Japanese Le Mans Challenge. The final year that LMP900 chassis were allowed ACO entries was 2006.

Fast forward a decade and progressive fuel tank and engine-intake restrictor measures were taken, aimed at equalising performance between hybrid-engined cars and non-hybrid-engined designs.

Until 2016, LMP2 allowed both open and closed-cockpit designs while LMP1 allowed only closed-cockpit design. Although a passenger seat is not used, cars had to be designed to accommodate two people. Only production-based engines were allowed in LMP2, and from 2013 diesel engines were permitted.

Of course costs of creating and campaigning such cars rocketed. The FIA introduced optimistic economy measures, and a Nissan-engined LMP3 class was added. Still, cheerful racers navigated their way through such complex and turbulent regulation changes to run some of the most excitingly fast and capable enclosed-wheel racing cars any enthusiast could ever hope to see – and we will be enjoying a selection of them – regardless of their background in pettifogging bureaucracy – at the forthcoming Members’ Meeting. Never mind the paperwork – just enjoy the intricate design, and ingenuity, and construction, and the sheer, pure speed of these things…