Tested: Pickup Truck Mirrors

[Big Dave]

My truck came with telescoping trailer-towing (TT) mirrors. Unless pulling a trailer, I always run with them pulled all the way in. They are flat-out the best side-view mirrors there are in terms of seeing what is behind you. With my totally opaque bed fairing I need them. These are OEM optional mirrors.

But they are enormous. They have a little effort at rounding off the forward side, but they have to impose a lot of drag.

Another option is the factory "paddle" mirror. They are smaller and do not extend out as far from the cab. They don't give you quite the view to the rear, but it is good enough.

There is a lot of thought in the pickup truck community that the paddle mirrors should give better MPG.

Seems intuitive, but how much. We have also seen some counterintuitive results from aero mods. Only one way to answer the question. Road test.

After six weeks and 2539 miles of my circuit in nearly constant mild summer weather on flat terrain running my usual test circuit (35% urban/suburban, 30% Interstate at 1700 RPM (69 MPH), 35% stateroads at 1450 RPM (60 MPH) with some moderate hypermiling (mostly coasting and timing lights plus bump-and-coast in town) I got a result.

The paddle mirrors delivered 0.66 better MPG or a 2.5% improvement.

TT mirrors: 26.32 MPG
Paddle mirrors: 26.99 MPG

Note: I ran the test without my air dam. It is undergoing a redesign, so I am down from last summer a bit. I did not get to do a pure Interstate run where aero improvement would have really shown.

Just thought you guys would like to know.

[Deezler]

Need pics!

I guess that sounds about right (2.5%) though... prolly more if your truck weren't so huge-normous.

Good mpg record keeping!

[winkosmosis]

I don't think that difference is outside of the margin of error, especially since you're looking at a mixed driving route with no consistency between tests. What you're comparing is average mpg of two long periods of time, and coming up with only a 0.67mpg difference.

A Scanguage reading both ways, on the same day, at the same speed, at almost the same time would be ideal.

[Christ]

I like how you got 26.99 mirrors using the paddle mirrors...

[RobertSmalls]

What Winkosmosis said. My fuel logs are up and down 5% for no discernable reason. The fact that you have 2500 miles of logs helps, but I still think other things (ambient temperature, average air density, driving style) can have changed.

Scangauge testing would give you more data points and a higher sample size, but what you need is controlled coastdown testing.

[MadisonMPG]

Smaller mirrors= better mpg... nothing else needs to be said.

[FastPlastic]

Originally Posted by MadisonMPG

Smaller mirrors= better mpg... nothing else needs to be said.

I agree. We all know the wake created by an object is one of the most important points to address. Smaller mirrors = smaller wake = better mileage.

[Christ]

Originally Posted by FastPlastic

I agree. We all know the wake created by an object is one of the most important points to address. Smaller mirrors = smaller wake = better mileage.

Don't forget the case with certain GM cars where removing the mirrors is actually worse for aero.

I can't find the article at the moment, but I believe it was newer Impala and Malibu Classic models that would suffer from mirror removal.

[Frank Lee]

I read about that too and had a hard time finding anyone who'd agree.

I think it was the big Caprice' from the '90's.

[tasdrouille]

Originally Posted by Christ

Don't forget the case with certain GM cars where removing the mirrors is actually worse for aero.

That was probably said by the same people who believe they get better mileage at 85 than 65.

The % increase in frontal would have to be compensated by an higher % decrease of the Cd. Highly improbable.