I don't know anybody that gets up in morning and pushes their 'ultimate driving machine' to the limit on the way to work every day. 90% of the time when I see a 335 or an M3 or even a Ferrari it is in traffic beside me doing the same exhilarating 40 mph as the rest of us. I think that means the EPA numbers are very important to the vast majority of consumers (even those of us who like to enjoy our car's potential when the opportunity arises). The only people I know that actually drive that aggressively on a daily basis are 16.
I think we would all take the N55 in a world of unlimited resources.
I have not driven the N20 yet, but I am excited that BMW is finding ways to improve efficiency, and still give us more and more powerful cars.