why the move to small engines ?

[StuntmanMike]

As title really, why is a 4 pot turbo more eco friendly than a 6 pot NA engine, for the sake of discussion lets say a 2 litre turbo 4 cylinder v a 6 pot 3 litre, I dont care what people prefer, or which will last the longest so please dont post with that rubbish, I am asking why one is dissapearing and the other thriving.

[StuntmanMike]

I see, I always held the simplistic view that a turbo turned a 2 litre into a 3 but that is a very good answer.

[StuntmanMike]

Thanks for taking the time to write all that, excellent post.