Peakster's First Formal Experiment a Success!

[Peakster]

With my dad coming back from Las Vegas on Monday, he's no doubt going to be asking why I removed the side mirrors from my Geo. Tonight I did an experiment to see the difference in FE with mirrors on Vs. mirrors off:

Date: January 13, 2007
Time: 12:30am - 2:00am
Temperature: -9.4*F to -7.6*F
Winds: SW @ 9.3 mph
Location: Regina's Ring Road Expressway... very flat road
Speed: 70mph with cruise control
Length of each test: 7 miles
Method of testing: A-B-A-B
Tools used: Scangauge II and Hi8 Videocamera

Route:
Experiment.gif

Results:
36.2 mpg (mirrors on)
36.9 mpg (mirrors off)
36.1 mpg (mirrors on)
37.0 mpg (mirrors off)

Average mirrors on: 36.15 mpg
Average with mirrors off: 36.95 mpg

Therefore 2.213% FE increase without mirrors during the above conditions.

All figures were average readings from the Scangauge II during each 7 mile test.

[TomO]

Very nice! One thing I noticed is the temp is "Temperature: -9.4*C to -7.6*F" which format is it supposed to be? Celsius or Fahrenheit?

Other than that, it's great to see more info supporting the removal of the side mirrors for increasing FE.

Makes me wonder more in my smaller more aerodynamic mirrors would be even better off the car completely.

[MetroMPG]

Nice test, Peakster

[CO ZX2]

Originally Posted by Peakster

Therefore 2.213% FE increase without mirrors during the above conditions.

All figures were average readings from the Scangauge II during each 7 mile test.

Good job, Peakster. Very thorough and scientific. I noticed the clock when you finished these tests. 12:30AM till 2:00AM. That is dedication. To give us an idea of what's involved in a good test, please estimate the total time you put into this project. P.S. time and flashlight batteries.

[Peakster]

Originally Posted by TomO

Very nice! One thing I noticed is the temp is "Temperature: -9.4*C to -7.6*F" which format is it supposed to be? Celsius or Fahrenheit?

Thanks for pointing that out. The temperatures are now both in Fahrenheit. The temperature cooled off slightly near the end of the experiment but the winds were stable.

Originally Posted by CO ZX2

Good job, Peakster. Very thorough and scientific. I noticed the clock when you finished these tests. 12:30AM till 2:00AM. That is dedication. To give us an idea of what's involved in a good test, please estimate the total time you put into this project. P.S. time and flashlight batteries.

12:30 - 2:00am was in fact the total time out in the Geo. Each 7 mile run took no more than 6 minutes at that speed so it was only really 48 minutes of driving for both the test and driving the car back to the starting point.

Actually that's a lie, the first run screwed up because when I started to accelerate, two vehicles merged on the highway and refused to leave the passing lane open, causing me to hit my brakes . Luckily I was only about 3 minutes into the run so it wasn't much loss of time.

The mirrors attachement and removal time were really quick. Maybe 3 minutes to take them off/on (I only attached them with one screw to the door). I left the Geo's engine run the whole duration, so the Scanguage didn't shut off at any time during the 12:30am -2:00am period to provide a more accurate reading between runs and so I can just hit the 'resume' feature on the cruise control for the next run.

However, if you really want to know how much extra time I spent preparing for the test itself, I was trying to look for an audiocassette recorder (for documenting mpg numbers) for a half-hour before settling for my camcorder!

[Hockey4mnhs]

very well done

[James]

Thanks for getting out there and doing it.

Note for those whom are removing their mirrors right now:
The mirrors probably have a much greater effect on FE at -7 deg F than under the average conditions many of us will be driving in.
Perfect conditions for illustrating the difference though.
Phil Knox found no difference in top speed with or without the mirrors installed on his CRX at 100MPH on the salt flats, so he determined that the effect on FE is pretty small compared to other aero mods.

[Peakster]

Originally Posted by James

The mirrors probably have a much greater effect on FE at -7 deg F than under the average conditions many of us will be driving in.

MetroMPG did a similar experiment at higher temperature with lower speed. With the passanger side mirror removed and driver's side folded back, his car netted a 2.3% increase in FE. Not a far cry from my results.

[Peakster]

I just put the video of my experiment on YouTube. Enjoy!

[SVOboy]

You're such a cutie,

Nice test though, very well executed.

[Silveredwings]

N-n-n-n-nice J-j-j-job!

[roadrunner]

Originally Posted by Peakster

I just put the video of my experiment on YouTube. Enjoy!

Nice video, Peakster

[scostanz]

Very nice test, thanks for sharing! I wonder how this translates to other vehicles though? Based on limited input, the results seem to be consistent with other Metro's but it isn't clear that you can transfer that to another model.

Just wondering.

-- Scott

[Peakster]

Originally Posted by scostanz

Very nice test, thanks for sharing! I wonder how this translates to other vehicles though? Based on limited input, the results seem to be consistent with other Metro's but it isn't clear that you can transfer that to another model.

Just wondering.

-- Scott

Mostly likely it would be different with various model cars. For instance, if I ripped the mirrors off of The Chevy, I probably wouldn't see much difference at all because the truck has huge frontal area anyway.

Because the Geo metro gets higher FE numbers, than most cars, the mpg difference is much more readable than if I drove the truck which gets 15 mpg to begin with.

[skewbe]

Peakster, Thanks for doing and sharing. 70 MPH is probably the biggest factor IMHO. My average speed is 25 so it wouldn't help me much, but people who use the hiway a lot certainly have much more to gain with the aerodynamic improvements, ANY aerodynamic improvements.

scostanz, true enough, it could be that the mirrors are effectively blanked out from the shape/location of the windshield/bug guard/grille on another vehicle. You cannot say for certain that this transfers to another vehicle, certainly the exact numbers wont. But you can make the generalization that less frontal area equals less drag, so it probably will help reduce drag to some degree.

If you are going slow, then the mirrors offer better situational awareness and reduced blind spot, and I would keep them. Only if you spend most of your time going fast would I suggest *considering* shaving off your outside mirrors (and then consider replacing them with a camera or at least one of those multi angle wide interior jobbies).

[MetroMPG]

Or do like I did: compromise - delete the pass. outside mirror (inside replacement) and fold back the driver's side on the highway, and deploy it for city driving.

Neat vid, Peakster.

[kickflipjr]

That was a well done experiment. -25 Celsius? Brrrrrr.

[landspeed]

Thanks for publishing this . I am going to try mirrors off, and try to break the invisible barrier of 50.6 (UK) MPG - no matter what I do, I can't seem to get past the number!.

Regarding the drag of the mirrors, it has already been mentioned that they add to frontal area, and are placed in a position where the air speeds up due to being forced around the car.

There is also a long column of turbulence behind the mirrors - a few days ago, as a passenger, I held a cup of steaming hot tea (from a thermos) behind the mirror, and the turbulence was very well demonstrated!.

[landspeed]

BTW, 0.2GPH is not bad for idle - it means that, coasting with engine-on at
30mph will be like getting 150mpg, while at 60mph, it will be 300 mpg!

[eivad1]

if u get a bigger inside mirror the delete of the outside mirror is that legal

[Peakster]

Yup, that's what I did. You can see it here.

[eivad1]

i wonder if its legal n cali