Overview
The American Le Mans Series uses essentially the same rules as the 24 Hours of Le Mans. Like the 24 Hours of Le Mans, there are 3 primary classes, though there are 2 extra "Challenge classes" using standardized cars. Purpose-built race cars with closed fenders compete in the Prototype classes P1, P2, and P-Challenge) (PC) and modified production sports cars compete in the Grand Touring classes GT (GTE-Pro and GTE-Am combined, formerly GT2) along with GT-Challenge or GTC. The former GT1 category was abandoned after 2009 season. In 2012, the "Le Mans" (LM) was dropped from the names of the prototype categories.
Each car is driven by multiple drivers (2 or 3, depending on the length of the race), and all cars compete together simultaneously. P1 generally contains factory teams while P2 contains privateer teams. In ACO-sanctioned racing all of the drivers are professional in GTE-PRO, while in GTE-Am, 1 or 2 amateurs are allowed to race with a professional driver in support. However since ALMS uses only one GTE category and combines the PRO/AM classes, there are no limitations for drivers.
The two "Challenge" classes are formula-based, and are designed for privateers or rookies to have an easier time entering the series. Currently, the Challenge classes use the Oreca FLM09 (P) and the Porsche 911 GT3 Cup (GT), though there are reports that the ACO may open the Challenge class to other manufacturers in 2013 or later.
The team points champions and runners-up in each class at the end of the season receive an automatic invitation to the next year's 24 Hours of Le Mans.
Read more about this topic: American Le Mans Series