Is it because the LMP program or the millions spend in R&D for road cars though? I have a hard time believing things like that wouldn't have happened if it weren't for the race team. The major car companies have insanely huge R&D departments, some have their own testing facilities as well(VAG is one of them). Le Mans is little more than a marketing campaign for new technology these days.
See above...
I don't see it having a realistic application on normal cars though, which is what were talking about(I think). Same thing with carbon fiber bodies, they may work for high end sports/super cars but don't really have much use on an average daily driver.
I'll admit I'm not extremely familiar with exactly how it works, but I can't imagine much energy getting stored from daily driving.
Relevant to what though?
Fuel efficiency on road cars? There have been fuel efficient cars on the roads for decades now.
Getting high fuel economy with less gas? See my response to the first quite.
Why would I? It's really the only saving grace of American sports car racing currently.