Better for MPG: A/C or Windows?

[iamkungfool]

I know mythbusters did this...but i missed that ep

Any opinions, factual knowledge, anecdotal evidence, chuck norris jokes or zombie comments are welcome.

[nick_danger]

I don't have any facts for you, but I know in my Magnum, opening any windows or the sunroof on the freeway results in a 2-3MPG loss. I notice nothing with the A/C on.

[Hurst Equipped]

it depends on fast you're going. at slower speeds the AC drains more power than the wind drag with the windows open. at higher speeds it is just the opposite, wind drag drains more than the AC.

[RandomAccess]

Mythbusters says AC.

[lbstone]

I'll confirm that I watched the Myth Busters episode and they say AC. They were going about 50 mph on the episode I think!

[hemiunderglass]

There's a little thing called parasitic drag that the AC compressor inflicts on the drivetrain. It can't help but debit fuel milaege. In a direct comparison the open windows would always win for better fuel mileage, but if you arrive at your destination all sweaty and wind blown is it worth the mileage saved? Not in my opinion!

[sxtowner]

ac on less drag
for you pickup owners gate up creates an air pocket that lowers rear drag on the cab so no gate nets or keeping them down. Mythbusters proved that one too.

[iamkungfool]

I used to do a little but the little did`nt do ..
~sxtowner

Rock on GN'R!!!!

We've been dancing with Mr. Brownstone!

[quarky42]

Even better: Vents. Find a temperature that the AC shuts off and have the fans on medium. *grin*.

I'll cruise with my AC at 69 though, thanks. It's a good temperature amongst other things.

[bellman25]

IMHO, i always use a/c on the highway, windows in city driving. that is unless its very hot then forget it and i turn the a/c on no matter what

[northeastern08]

I usually use my windows, but often I forget I have ac on and have my windows down at the same time....best of both worlds. Im so amazed at my mpg since superchips, a couple here or there doesnt really bother me. I used to get around 10-12 tops...now Im averaging 19-22 all the time.

[lbstone]

There's a little thing called parasitic drag that the AC compressor inflicts on the drivetrain. It can't help but debit fuel milaege. In a direct comparison the open windows would always win for better fuel mileage, but if you arrive at your destination all sweaty and wind blown is it worth the mileage saved? Not in my opinion!

The parasitic loss from the AC is less then the drag with the windows down. The scaveneged power from the crank pully is so minimal that it's not measurable in some of todays vehicles. I'm telling you, you have to check out that mythbusters episode they tested this on. They did a test using the vehicles own computers fuel consumption readings and also ran the two identical ford exploreres that they drained all the fuel out of and put the exact same amount in each one. The explorer running AC ran almost 20% farther at around 50 mph on a track.

[Matrix]

IMHO, i always use a/c on the highway, windows in city driving. that is unless its very hot then forget it and i turn the a/c on no matter what

What he said!