The dilemma for auto racing is that if race cars become silent, the sport may die. But are fans begging for hybrid race cars or electric race cars? Nope! Fans do not say "I will only like auto racing if the cars are green." Auto racing is supposed to be a thrilling sport, not a tree huggers paradise. People come to races to be thrilled, not be green. They do not give a hoot how many mpg they get. They want to see race drivers do the impossible at blazing speeds in flashy cars that sound awesome.
F1 stepped on their dick thinking fans wanted hybrid race engines. Nope, exactly the opposite. They loved the awesome sound of the old cars and fans were not standing around at race tracks carrying signs saying "the cars sound too awesome, please make them sound like sh#t." The new F1 engines are four times more expensive, sound horrible and the paying customer hates them. The power units are a nice engineering exercise that produced engines that belong in passenger cars, not race cars. It was an expensive lesson that all race series around the world should learn from and NEVER copy.