There's too many inaccuracies to take this as gospel but it looks to be ~3%, although I don't know if you're supposed to use the area under the car when calculating the benefits of lowering. I did this time, although I didn't when calculating the benefit of removing the mirrors.
I'm very seriously considering putting my passenger mirror back on. I don't feel comfortable with my reduced vision. I keep noticing cars moving into my blind spot, which is now much larger!
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