Just curious what setting you put your a/c on to be the most fuel efficient. We have an 06 4cyl with navi. I use the manual control most of the time but it seems to like the gas. Any idea what is best.

I tracked everything to a T for a year and didnt see a difference in the A/C season, so I dont know that it matters so much.

The only thing I ever change is the fan speed. Once the car gets good and frigid I'll turn the fan down......a little.

I think the compressor runs the same amount no matter using Auto, Manual, or varying the temp. controls. It will still be conditioned air, but the flaps that control the amount of heat added to the cold air will be what changes. I don't think fanspeed will affect mpg either.

I notice mileage drops a few in the summertime with the AC on 100%. I also just leave it on Auto and let the system do it's job. It does it very well (both our cars have ATC and we love it). If the fan speed is too much at any given time, dialing up the temp control a bit solves that but still keeps it in Auto mode. :)

For some odd reason, I do not see any substantial hit in mileage during the hot summer season with the A/C on all the time...I leave the A/C on, temperature setting at 78F, and fan speed at 2 or 3...I do not use the re-circ at all...

I ran it most of the time last week. Averaged 30.5 MPG on 385 miles with 80% of that highway.

I CONTROL the compressor. I shut it off when it is cold and turn it on when it is hot. If I save it from cycling 50% of the time, I figure it's worth the effort. Especially if it is saving just a little gas.

I design commercial HVAC systems. Why we pay $25k for a vehicle that has the very simpliest HVAC system I will never figure out. Until we as consumers demand conditions-controlled compressors, two-speed compressors, etc., in our cars, we are burning more gas and using more HP than we need to in vehicle HVAC systems.

So you all are saying that you see no decrease in gas mileage when using the A/C, compared to the winter months, when the A/C is off?

I dont think I would pay for a more efficient compressor on the car because I cant even tell its even changing my gas mileage to have the AC on. Did anyone watch the mythbusters about using the A/C v the windows?

Did anyone watch the mythbusters about using the A/C v the windows?


Yeah, that was one of those episodes I did not agree with. I can't remember my reasoning but there was something off about the test that didn't sit well with me, still can't remember what it was tho. It could also be the fact that during last summer I averaged better mileage with my windows down and no a/c than with windows up and a/c on.

It could also be the fact that during last summer I averaged better mileage with my windows down and no a/c than with windows up and a/c on.
I always thought that having the A/C on sucked up the gas. Seemed like it in every vehicle I've ever owned. :dunno:

Did anyone watch the mythbusters about using the A/C v the windows?
About how long ago was that on?

*** EDIT ***

Found a couple of links. Seems like it was about three years ago...

http://kwc.org/mythbusters/2004/11/mythbusters_boom_lift_catapult.html
http://en.wikipedia.org/wiki/MythBusters_(season_2)#Episode_22_.E2.80.94_.22Boo m-Lift_Catapult.2C_AC_vs._Windows_down.22
http://community.discovery.com/eve/forums/a/tpc/f/9801967776/m/7441914198

Also, I found a link discussing the question of aerodynamics with the windows down...

http://www.newscientist.com/backpage.ns?id=mg18925432.200

So you all are saying that you see no decrease in gas mileage when using the A/C, compared to the winter months, when the A/C is off?

It knocks mine down about 2-2.5 mpg I suppose but that's the small price of being comfortable to me. When it's 95+ with 87% humidity I want cold air and could care less about a few MPG.

The hit you take with AC might be offset by the warmer and less dense air. I don't know if it affects me much...I never use AC :dunno:

I run mine quite a bit on auto now, mostly highway miles. I see no difference...in fact, my mileage has been steadily increasing over the past month or so. :dunno:

I run mine quite a bit on auto now, mostly highway miles. I see no difference...in fact, my mileage has been steadily increasing over the past month or so. :dunno:

Have also recently been getting about 2 more MPG since mid April. Maybe a new blend or less time on the fuel enrichment circuits on cold starts are the reasons. :dunno: Anything helps with fuel prices above $3 pretty much everywhere.

I think Benji has it right its probably tough to tell for a lot of us because the air the engine is taking in isn't the same during the times we feel we need AC vs. the times it doesn't.

Hmm. Guess I'll need to throw the A/C in as a test variable for my fuel economy. I'd like to see if there is any difference between windows up w/ A/C on and windows down w/ A/C off...

BTW - A little off topic, but...

I always thought that having the A/C on sucked up the gas. Seemed like it in every vehicle I've ever owned. :dunno:
The hit you take with AC might be offset by the warmer and less dense air. I don't know if it affects me much...I never use AC :dunno:
I run mine quite a bit on auto now, mostly highway miles. I see no difference...in fact, my mileage has been steadily increasing over the past month or so. :dunno:
Have also recently been getting about 2 more MPG since mid April. Maybe a new blend or less time on the fuel enrichment circuits on cold starts are the reasons. :dunno: Anything helps with fuel prices above $3 pretty much everywhere.

...I think I might just call this the "dunno" thread! LOL! :D

Or maybe it's just me. Dunno. :dunno:

I seem to be consistently getting 25.8 to 25.9 mpg with my '06 AV6. Mostly with A/C on. This is about 70-75% highway mix.

One thing I HAVE noticed with AC off is the increase in acceleration/power. Not a huge increase, but it is noticable.

I've been getting better mpg the past few months as well. In the winter I usually got around 25, but there were quite a few times the car warmed up for 10+minutes. Even last summer I got 27.5 at best, but the last two tanks I've been at 29. This is in a v6 auto 70ish% highway. I've also been driving a bit better this year, so thats probably where the increase is from:D

I don't use the ac that often though. Maybe 20-30 miles a tank, and than I just set the control at 75degrees. Otherwise I just have the sunroof open.