I'd like to see that comparison between a F1 car and LMP1 car. considering that the LMP1 actually produces more downforce than a F1 car it should be interesting.
I do not think it is about being green. If anything, it is about keeping some kind of connection between the tech used in F1 and what eventually ends up in production cars. For example, Honda will be returning to F1 in 2015 to make engines for McLaren. Producing a few V10s for a constructor has no real tie to their core business, but a turbo V6 is very much in line with what their consumers are interested in.
Is it really about green? I thought it was more about enforcing cars that cost less to maintain throughout the course of a season. They have been heading that way for a long time, restricting teams to a set number of engines and gear boxes per season.
Its about attracting manufacturers with using engines which closer match the engines they sell in road cars. Ok, they happen to be greener, but add in the dev costs and these engines are more expensive.
