Both my mirrors fold against the door side glass and since they are probably in a air pocket coming off the windshield they probably don't affect the mpg much - I also think a hood mirror just in front of the windshield where the bubble of air dams up against the windshield would work for a rear view mirror and you would be looking out the windshield to see it which means it would be clear in the rain and the snow. Better yet a tiny camera on a small aero boom where the mirror would normally go connected to a TV screen inside the door or on the dash would be cool too.
You would think that a clear boat tail on the mirrors would work maybe on the outside edges and be able to see through them as well. Or a long thin mirror right against the window of the door but only a couple of inches wide would work as a wind deflector and mirror at the same time.
On my car, I already use the big fisheye mirrors for trucks on the outer part of my mirror (about 3" in diameter). Currently I use the fisheye mirror to see what's in my blind spot, and then I use what's left of the flat part to figure out how close it is. I think that with the 17" panoramic, I could get away with a fisheye on the interior of the car.
Here is a website that has *very* expensive racing mirrors :
Maybe 20 years ago I bought the Sebring Mirror style. It was a cheapo from JCWhitney, but it has the flush aerodynamic shape that I wanted (I am going to look for it!!!!). I'll bet that a mirror like this could help you comply with the legal requirement, reduce your drag, *and* look cool at the same time! Here is an example mounting (that's not me) :
Question : How about the "ultimate" fisheye? I mirrored ball on a stalk? What are the aerodynamics of a sphere?
Stuck my hand out the window the other day at about 35 mph and there is some really fast moving air going past the mirror area. One of the nice things about outside remote mirrors is the ability to rotate them down and inwards to see the rear tire while driving - may prove helpful in rain to see what the air flow is doing back there. Note that the law states there has to be a mirror not that it has to be outside. Whatever happend to the roof rear view mirror systems using that dead air space right above the windshield?