do you think your instant MPG measures increased drag? instantaneously? seems like the drag factor wouldnt be immediate but would contribute over a long period of time.

 

It will guage drag instantly. On the hwy if I duck behind a semi it will jump right up and if I pull out from behind it goes right down.
Thats the whole point behind the instand mpg to see what your getting at that point in time. I think your thinking about the average mpg read out which wouldn't show until a long period of time.

 

no i have never dealt with any of these indicators, on my 00, there isnt any of that other fancy computer information center stuff. so i know nothing about it. cool feature though. ill be posting up my findings when i fill

 

i think the mythbuster had 2 explorers or expeditions for the A/C test on the circle track.

Wonder why they always test the fords??

hahah

 

I would wash and wax the truck thats good for at least .74635295211333 MPG.

 

I stopped worrying about my mileage when I realized that I wasn't gonna get rid of my truck or drive it any differently! It sucks, but thats the way it is for me. Unless gas gets really outrageous, I'm gonna ride on!

 

Mythbusters DID NOT bust those "myths." This particular episode of Mythbusters is why a no longer watch Mythbusters.

Their test was to run two identical Ford Explorereditions around a test track with the following three conditions:

1. Windows UP, A/C ON.
2. Windows UP, A/C OFF.
3. Windows DOWN, A/C OFF.

The first three tests were done with Ford engineers with a scan tool calculating mileage off the MAF. They drove the test circuit at 55mph for several laps and recorded the following (I'm making up numbers, because I don't remember the exact figures...but these are close enough):

* Windows UP, A/C ON: 14MPG
* Windows UP, A/C OFF: 14MPG
* Windows DOWN, A/C OFF :13MPG

That was at 55MPH.

The track safety official was petrified seeing the Exploreditions on Firecrap tires circling the track at 55MPH. The tires were getting hot and being torn up.

The Mythbusters second test was going to be to run configurations #1 and #3 in two different trucks and see which ran out of fuel first. The track official said NO, you're not going to drive those trucks for x hundred miles at 55mph, you're going to blow a tire before you finish.

So the Mythbusters siphoned all the fuel out of the tanks, and added 5 gal to each. Then they agreed to conduct this second test at 35MPH. A/C on ran out of fuel first at the slower speed. "Myth busted" because they felt the results of the second test were more "real world" or some BS like that.

Morons.

Drag = 1/2 rho v^2 * Cd * SA

rho is air density
Cd is coefficient of drag
SA is the reference surface area for the drag coeff
v is velocity

v^2 @ 35mph 35*35 = 1225.
v^2 @ 55mph is 55*55 = 3025.

So at 55mph there is 2.5x as much aerodynamic drag as there is at 35mph. Aero drag is only one part of vehicle efficiency. At 35mph, the drag resulting from the decreased aerodynamics of having the window down was less than the parasitic loss of turning the AC compressor. At 55mph, it was the other way around.

The mythbusters did not discuss any of the above. They didn't think seem to the speed difference mattered. It was just "myth busted" and that was that.

As far as the tailgate up and down....the tailgate up should work better as believe it actually reduces the net drag on the truck. A boundary layer forms in the bed. There's basicly a layer a stagnant air sitting in the bed, acting like a "virtual" bed cover. So you're not actually seeing as much drag as you might think from the tailgate and such. With the tailgate down, that boundary layer goes away, and you get increased drag from the huge drop off after the back wall of the cab. Some university in Mich or MIT did a study on this with a real truck.

 

Did you write in to tell them that?
They do "revisits" on certain episodes where enough viewers write in.

 

I'm not calling you or your information wrong, I'm just wondering why it's the opposite for me...

 

im suire there are a plethora of factors that could explain, i wasnt going to touch the tailgate test really until i decided what the hell because the news paper already did a test on it and it made great sense , its like watching an empty coke can in the bed of your truck, doesnt usually fly out, just kinda floats around, sure as hell not going 70mph...im glad this has sparked some interest though