Side mirror drag & effect on fuel economy - quantified

[cfg83]

WaxyChicken -

Originally Posted by WaxyChicken

Rather than completely remove the mirror on the driver side and replace it with an uncomfortable in-side side mounted mirror, why not aero mod it? give it a boat nose and add wind spreaders to the top side.

...

I like how your thinking. On cars where the mirror is part of the door, other people have suggested a clear plastic cover that moves the air over the mirror while allowing you to still see the reflection.

CarloSW2

[MetroMPG]

I think it's safe to say that most vehicles would be improved by a mirrorectomy.

The only way I could see it not helping is if the mirror is already fully involved in turbulent flow from, say, really unfriendly windshield/A-pillar design. Like perhaps the Jeep TJ style.

[Frank Lee]

I've read the bubble Caprices' lose aero from the removal of mirrors. Where that knowledge came from I can only guess... perhaps the cops figured it out? Anyway it seems plausible to me.

[MetroMPG]

Well, it sounds a bit odd to me, but I'm no expert. I'm just going by book stuff & what seems sensible to my mind. But I'll readily admit sometimes aero is counter-intuitive.

[PaleMelanesian]

I heard that same thing about that same car. Don't remember where. However, I'd guess that in 99.something % of cases, it does add drag.

[tasdrouille]

It does not make sense that removing mirrors on a car would add drag. Removing mirrors lowers the CD and the frontal area, it's a win win situation. The only way a mirror could reduce drag vs no mirror would be if it was in the wake of a bigger object.

I would like it a lot if you could link to some background information supporting your affirmation.

[PaleMelanesian]

I've read dozens of papers and articles about aerodynamics. It was a small side-comment in one of those. Apparently Frank Lee has read that same one. I do not remember where it was.

[tasdrouille]

All I could find was some guy over at gassavers saying that some other guy posted a reference to that effect a while back, but I wasn't able to find said reference.

One thing I can think of though is that this might be a confusion as in 1995 they changed the mirrors to more aerodynamic ones. Here's a comparison between a 94 caprice and a 96. See how the mirrors are like an extension to the A pillar in the 96 pic.

94


96

[Frank Lee]

Kind of like Carl's quote, if there's anything I've learned over the years, it's that there's a lot in aerodynamics that is counter-intuitive.

[tasdrouille]

All I'll say is that It's pretty bold to say something going against what is commonly accepted when you have no hard evidence to support your claim.

Aerodynamics can be counterintuitive, I concede, but it ain't magic.