In the ACO regulations, two categories of sports prototypes are now recognised: P1 and P2. Cars competing in the P1 category must weigh no less than 900 kg and are limited to 6000 cc naturally aspirated and 4000 cc turbocharged engines. 5500 cc turbo-Diesel engines are also permitted in P1 – Audi scored Le Mans victories with such a car in 2006, 2007 and 2008 and Peugeot returned to racing in 2007 with a car with a similar powerplant (Peugeot 908). P2 cars can weigh much less — first 675 kg, then 750 kg and now 825 kg — but are restricted to 3400 cc V6 or V8 normally aspirated or 2000 cc turbocharged powerplants. In the European series in which endurance is a priority and P2s have been run largely by privateers, P2s have not challenged P1s for outright victories; in the American Le Mans Series with generally shorter races P2 has become the most active prototype category with serious involvement from Porsche and Acura and whereas P2 in Europe tends to involve races of attrition, in the US series the P2s, particularly the Porsche RS Spyder are often quicker round a lap than P1s, with the Porsche having scored many overall victories against the Audis in P1.
In the ACO regulations two categories of sports prototypes are now recognised P1 and P2 Cars competing in the P1 category must weigh no less than 900 kg and are limited to 6000 cc naturally aspirated and 4000 cc turbocharged engines 5500 cc turbo-Diesel engines are also permitted in P1 – Audi scored Le Mans victories with such a car in 2006 2007 and 2008 and Peugeot returned to racing in 2007 with a car with a similar powerplant (Peugeot 908) P2 cars can weigh much less — first 675 kg then 750 kg and now 825 kg — but are restricted to 3400 cc V6 or V8 normally aspirated or 2000 cc turbocharged powerplants In the European series in which endurance is a priority and P2s have been run largely by privateers P2s have not challenged P1s for outright victories; in the American Le Mans Series with generally shorter races P2 has become the most active prototype category with serious involvement from Porsche and Acura and whereas P2 in Europe tends to involve races of attrition in the US series the P2s particularly the Porsche RS Spyder are often quicker round a lap than P1s with the Porsche having scored many overall victories against the Audis in P1