Some rough calculations:
stock mirror = 5,2 l/100km@97 km/h or 45.27 MPG us @60mph:
Aerodynamic & rolling resistance, power & MPG calculator - EcoModder.com
My mirror desing rough estimation:
- delta Cd= 0,010 ( no mirror at all =0,012 drop in cd)
- Frontal area reduction 0,0298m2=calculation based on my lupo 3l mirror frontal area drop
-->5,01l/100km@97 km/h or 46.98 MPG us @60 mph
http://ecomodder.com/forum/tool-aero...ToStep=5-200-5
That is roughly 0,19 liter or 3,7% difference FE at 60 MPH
Take mirrors out:
delta cd in CFD program =0,012 (0,017 in wind tunnel test)
Frontal area drop = 0,0456m2
--> 4.95 l/100km@97 km/h or 47.5 mpg us @ 60 mph
http://ecomodder.com/forum/tool-aero...ToStep=5-200-5
That is 0,25 liter drop from start or 4,9% effect at high speed driving.
Cd estimations are made based on this wind tunnel study:
http://publications.lib.chalmers.se/...ext/143193.pdf
I would say my mirror design has even bigger impact to cd than that 0,010 but that is a safe bet as not all cars are the same aero wise...