Addition of various racing KERS systems, along with all of it’s implementations (energy recovery adn deployment could be set with in the quick actions menu), from the least to the most powerful:
Tier 1- 440 or 450 HP (Similar to the 919 Evo’s KERS system power)
Tuer 2- 407 or 408 (Similar in power to the R18 '16 and the 919 LMP1 respectively)
Tier 3- Something in between given options
Tier 4- 160 bhp (Similar to current power in F1 cars)
Tier 5- Something lighter with less power
MGU-K upgrades on each Tier along with it’s consequences (oversteer)
MGU-H upgrades on each Tier (while adding oversteer on corner entry, this may solve the Cadillac LMd-h understeer issue)
This can be implemented in any car, or as many as possible. Please comment if you have better ideas or a better way for this to be implemented.