A/C Effect on MPG

This is a pretty general question, but I've always wondered how the A/C effects your MPG. I know it cuts the power of the car, so does that balance out the power the A/C is taking?

AC takes about 5 hp to run. So turning it on will lower your milage.

Windows suck about the same power power as A/C does. Best option is windows up A/C off (not likely lol). Although this reminds me of a WRC team that put A/C in their car on one of the hotter rallies. They lost some power, but did pretty well since the drivers where not baking as much. Race cars tend to get pretty freaking hot.

I see a drop of 2-3 mpg on average with AC running, it also feels like my 300lb brother is in the car too.

just got back from outer banks nc with our legacy...on the way down we ran with sunroof and windows open and averaged almost 33mpg(32.7)

waaay better than ida guessed..that was mostly nite driving and little traffic..on our way home we had to run the a/c on 3 most of the way home in 100deg heat with heavy traffic and averaged 27mpg...this is only what our readout in the car said, not what i obtained myself..we had to keep the pup and our fudge cool though theres so many variables in mileage its crazy, but gives you an idea...suprised we got 27mpg on the way home, ran into 3 accidents..one in dc area where we were in 1st gear for 20 miles just crawling and the a/c pumping..me myself i hate the loss of power and mileage with a/c on

They say in the city that windows down is the way to go, on the highway use the AC, if you're looking for fuel economy when it's hot.

Didn't myth busters run a thing on this?

I think they concluded that at highway speed, windows down caused about as much drag, if not a little more than the AC did, so AC was more comfortable, and a about the same fuel wise.

I wish i could find a link!

I usually see a 2mpg drop with the ac on.

40 mph is the point at which the drag from having windows open will start consuming more fuel than the AC.

40 mph is the point at which the drag from having windows open will start consuming more fuel than the AC.

 

^not being a smartass but where did that number come from. I have a very hard time believing that 40mph with windows down = ac draw. 60mph I can totally imagine but 40mph is not THAT much wind (per my years on motorcycles).

 

Maybe it is because ...

 

I see a drop of 2-3 mpg on average with AC running, it also feels like my 300lb brother is in the car too.

 

BoozeRS05's 300lb brother lives inside my AC and only comes out when I turn it on.

88% of statistics are made up.

I always try to avoid turning on the A/C no matter what. I'll just roll windows down and turn the fan on.

88% of statistics are made up.

This is an accurate assumption and very funny!

 

I have a saying for this sort of conclution that goes something like...

 

"you can't teach an old dog by it's cover, AND eat it too?"

 

One thing I like regarding the use of AC or not is the comfort provided and I advocate comfort and yes, perhaps spending a bit more on fuel would appeal to the special interest groups that also advocate the same thing...but you thrifty folks then consider the expense later of paying a very high dry cleaning bill to get the sweat out of your suits...but that's just me.

 

Another unmentioned aspect regarding the AC feature in our cars is that we have the choice to use it or not, when we wish, windows down or halfway up, etc and it's use is not (YET) subject to the control of others...some who may wish us to be uncomfortable as possible by definition and have yet to regulate this feature on our cars...say a Government requirement on odd or even days for AC use? How about a law to always allow officers clear view as to wearing our seatbelts or perhaps registering our cars in States that we happen to wish to visit on summer vacation immediately upon entering said State? More visits to the dreaded DMV? Read on:

 

Interestingly enough, the above was the subject of a ticket I got yesterday from the CA highway patrol for driving my Oregon registered vehicle in California (with my seatbledt on) as I also own property here in CA and like at times to come and visit my vacation home here...as at times it's snow bound or god awful hot or...

 

Go figure? The officer said he didn't see my seatbelt on, when I passed (and that was why he pulled me over) him leaving the shade tree he was parked under to tell me this? He noticed that I was wearing it when he came to the window, but wrote me up anyway...hmmm..

 

When the Government starts telling me/us when we can use AC and when we are not allowed to (as they essentially do now) in our homes for instance.... and here, given the scare water resources, the " don't water your lawn " and just let it die in the interest of the lives of other's ...hmmm and consider the electrical outages caused by heavy AC use on hot days and the special rates handed out to people that like to sweat more than others...it all gets so confusing?

 

Enjoy your choices while you can, I say!

 

and someone, please...

 

if you would...respond to my thread posted today regarding my dilemma on the Legacy GT MT wagons vs. Outback XT MT and their individual vehicle handling dynamics...(Outbacks have a 3" ground clearance advantage, does this significantly affect road handling on otherwise similarly equipped H4/MT vehicles?

 

http://legacygt.com/forums/showthread.php/all-you-outback-lovers-commenti-141804.html

 

PS: As a non-sweater in 104 heat today...I do encourage full use of my car's AC system..windows up!

 

 

Ran

Car & Driver or Motor Trend did an article on this a year ago. I forgot the total results but the final conclusion was that using the A/C resulted in better mpg results, although I believe the threshold for better gas mileage with the windows down was either 30/40mph.

The test consisted of different windows down configurations including the sun roof.

its hard to keep the ac off when its auto.... lol

I have used my AC more the past 3 or 4 weeks then ever, I also tend not to beat on the car as much in the HOT weather. This tank full I'm getting 22.8 on the dash. This is the best mileage I've seen in a while. I normally average 21.5-22.5 on the dash during the summer.

I just started using my AC this summer. I got used to how annoying it is to drive a manual car with the A/C on, and the last 1000 miles my LGT's MPG counter says I've gotten 24.6 mpg, and usually it read a bit lower than that when I used to drive around with the windows down constantly. I don't recall drastically changing my driving habits either.

AC takes about 5 hp to run. So turning it on will lower your milage.

It feels like the car loses alot more than 5 hp when you turn it on though. Amiright

never felt the difference. I do feel the difference when people get in the car or if i'm packing some weight in the trunk.

I usually average about 23.7 mpg on the in-dash, this tank I'm at 23.1 mpg using A/C. Not a huge hit, but a hit none-the-less. Of course, this will all depend on what kind of driving you do. I do almost all city driving.

+1 , my same sentiments. I lose 2-3 MPH and feels like two reg peeps in the car .

 

I see a drop of 2-3 mpg on average with AC running, it also feels like my 300lb brother is in the car too.

How about running the AC AND a full car...

 

I keep light work gear organized in the space behind my seat intentionally so if asked, I can only fit 3 people. My car is dropped and it has scraped before too.

While on the subject, is there any reason you can't romp on the car when the A/C is going? It's so sluggish with it on, and in "I" mode, that I get frustrated and take it out on the car by really getting on it.

Minimum 3 mpg loss running my A/C. In the city its closer to 5 mpg

Mythbusters covers this (although not as completely as I would have liked) in episode 22 of the 2004 'season'. Same episode as the boom lift catapult.

 

I seem to have seen that '40 mph' figure in all sorts of places, but I will still usually roll with my windows down at 40...anywhere over that and I switch to AC.