for a few years now. The tech is trickling down to road cars (Audi e-tron, Porsche 918) and the racing is excellent. The cars are fast and reliable. They even sound good...
Too bad Nissan sucked so hard with the LM Nismo GTR, hybrid system was a complete failure while Porsche Toyota and Audi are doing fine through proper development.
Wish Nissan would have the cajones to actually build this hybrid: