My mirror vison was not perfect, but good enough on proto parts. Biggest problem was that all 3 sides were joined to together, so if the sun was from behind it gave some reflections. Also the surface was not fully mirror due to low budjet and my oven manufacturing and vacuum forming methods...
I did make tuft testing and tufts were fully attached
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Solution is to have similar cover, but not make it teardrop in car heigth (Z) direction. So only teardrop the mirror cover in cars width direction (Y).
Mirror footage is starts at 5.20-
It is positioned high to avoid that high speed air flow at A-pillar corner but also the have it at my eye level
Quite back to get wider look angle and more cool air flow for the driver
My mirror is wide angle so I do not have any blind spots there.
I can make a improved version if you would like to buy them?
I did also make some calculations of the mirror drag:
Frontal area is about 75mmx105mm=0,00788m2 vs regular Lupo 3L mirror (this is smaller than most mirrors already) 120mmx190mm=0,0228m2. That is 2,8 times smaller
This design will lower your fuel consumption about 2-6% depending on the car.
Those race type mirrors that hang at some distance from body are 5 times worse visibility wise compared to my setup. My customers A2 has those and there is very big blind spot there.
Mirror frontal area is pretty much same.