[gwyllion]

The official explanation for the strange decision to go for 2 MJ ERS:

After testing various energy recovery systems, Audi decided to compete in the class of up to two megajoules of recuperation energy at Le Mans. The energy exclusively flows through a motor generator unit (MGU) at the front axle and is stored in a flywheel energy storage system. “We opted for this concept following extensive testing,” says Head of Audi Motorsport Dr. Wolfgang Ullrich. “In our opinion, it provides the optimum balance between efficient energy use, size, weight, energy conversion efficiency, responsiveness, drivability and a favorable operating strategy – combined with durability, which is the basic prerequisite for success at Le Mans.”

source: https://www.audi-motorsport.info/v2/...single/id/8495