After having my passenger mirror folded in 99% of the time for over a year, I finally removed it. I made a block off plate for the holes in the door from a piece of carbon fiber I had and used the existing hardware to fasten it back on to the door. I'm not completely happy with how it looks, but it's growing on me. You can see in the background my other Miata that still has it's mirror on for reference. Since removing the mirror I did a 130 mile round trip drive and averaged 44 MPG! I did keep my speed around 40-45 the whole time though.
edit: oh, and my clutch is on it's way out, so a lightweight flywheel and OEM clutch has been ordered.