Cars entered in the European Le Mans Series fall into two main categories, prototypes and GT. Each is sub-divided in two categories:
LMP2 (Le Mans Prototype 2) and LMP3 (Le Mans Prototype 3) and LMGTE (Grand Touring Endurance).
Below are the links to the main technical specifications for each category. In order to balance power output between different makes, cars are equipped with air restrictors. Their diameter is varied according to the engine configuration and weight for GT cars.
ELMS 2018 Sporting regulations HERE
ELMS categories and their technical regulations HERE