MPG: Summer and A/C
As soon as temperatures get into the 40s, my mileage increases dramatically. Now that it's summer, I really appreciate air conditioning. Not only is the car cooler, but it is also quieter.
People have been arguing about MPG and A/C since that luxury became available. I have never been able to determine a gas mileage difference between driving with and without air conditioning. I take the same routes several times during the week, and my average mileage per trip is always different. Turning on the A/C doesn't make a difference I can document. Speed makes a huge difference, but I can't see any difference at all when using air conditioning. If I take the Interstate on a thirty-mile trip, I'll average about 44 MPG, but if I take the back roads, I can average 50 MPG or better. I see no difference using or not using A/C, so I'm not going to suffer in the summer heat for a theoretical MPG difference. . |
Agreed. I might see a maybe 1 MPG or so difference but it's not huge when factoring all the other variables on my daily commute. I just filled up yesterday and got 42.9 MPG, that's using A/C and non-econ. Econ and A/C just feels really unresponsive so I avoid it. I've done it in the past and gets about 1 MPG better, but it's miserable to drive.
Still beats the 17 MPG my 4Runner gets so I'm not complaining too much :) |
I was wondering the same thing, so I tried a little experiment to introduce A/C as the only variable in MPG calculation, to see what effect it might have in real time.
If you engage cruise control while you're on relatively flat terrain, watch the MPG gauge as you turn the A/C on and off. Mine drops by 3-4 blips with the A/C on. |
Originally Posted by 2Rismo2
(Post 1403085)
Agreed. I might see a maybe 1 MPG or so difference but it's not huge when factoring all the other variables on my daily commute. I just filled up yesterday and got 42.9 MPG, that's using A/C and non-econ. Econ and A/C just feels really unresponsive so I avoid it. I've done it in the past and gets about 1 MPG better, but it's miserable to drive.
Still beats the 17 MPG my 4Runner gets so I'm not complaining too much :) |
its too hot without a/c. i dont care for a 1-2mpg even 5mpg difference. a/c stays on.
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Originally Posted by kenchan
(Post 1403091)
its too hot without a/c. i dont care for a 1-2mpg even 5mpg difference. a/c stays on.
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the ecoRoute thingie? those things work real well, i had one in my old hobby car with a garmin too. :nod:
did dat thing provide oil temp or just the coolant temp? i forget.. really need to see the oil temp. |
Originally Posted by kenchan
(Post 1403096)
the ecoRoute thingie?
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my scangauge2 has a reading for gallons per hour. when I turn on the ac, my idle GPH reading goes from like 0.16 to 0.27 or something like that. can provided pics and better numbers if you care
https://cimg4.ibsrv.net/gimg/www.fit...ad1fd11479.jpg TL;DR = its a tiny diff, just use the AC (esp on the highway) side note: If I recall, Mythbusters discovered that .... at low speeds, windows down is fine. at highway speeds, window down makes mpg worse .... or something like that. AC vs Windows | MythBusters | Discovery |
Originally Posted by kenchan
(Post 1403091)
its too hot without a/c. i dont care for a 1-2mpg even 5mpg difference. a/c stays on.
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The people who don't see a difference, I don't suppose your default vent setting is windshield defog?
... because the AC is always on in that setting. Personally I certainly do see a difference with and without AC, but at highway speed having the window open is just as bad, so assuming you don't like to boil I would just turn it on and ... if you really care about mpg ... slow down by 5mph which gets you, rough rule of thumb, 1mpg. |
I have noticed that my MPG has been going down since summertime started. But I'm also one of those people that keeps the a/c on full blast most the time so that is to be expected.
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Summer gas may be different and give lower mileage.
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Over the 92k miles I've had my 2015 Fit, most of them on a regular commute route driven repeatedly in similar conditions (so I'm comparing like with like), I'd guess that having the a/c on costs around 1 to 2 MPG.
Two other factors that make a significant difference are whether the air intake is set to recirculate or suck in from outside (recirculate saves around 0.5 to 1 MPG in freeway cruising, I would guess) and the temperature of the outside air. Once that goes into the 90s (of Fahrenheit) and above, MPG takes a hit. We've just had a very hot week for June (afternoon temperatures of 110-115), and my commuting MPG dropped from low 40s to high 30s. |
Originally Posted by Brain Champagne
(Post 1403215)
Summer gas may be different and give lower mileage.
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I've noticed about a 2 mpg difference, but.....not enough to not run the AC …. I sweat enough in a 12 hour shift, am absolutely running the AC when I want to. And, fwiw, I always notice my mpg improves when they switch to "summer gas" …..so in the late spring/early fall (pre and post AC needs), I get really great mileage just tooling around town....stop and go surface streets, no hwys, steep hills and curves. AC puts a hit on it, but that's OK....I have such bad seasonal allergies that I rarely drive with the windows open anyway
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Originally Posted by Brain Champagne
(Post 1403215)
Summer gas may be different and give lower mileage.
Good guess, but it's just the opposite. |
Winter gas is formulated to be more volatile so it vaporizes more easily in cold temperatures to help start your car. This added volatility is removed in summer gas because the gas would lose too much in the way of fumes and vapors in the warm temperatures adding to local pollution levels. And yes, summer gas gives slightly better gas mileage.
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I really don't see much difference in mileage when running the A/C. At least not compared to other factors that seem to have a bigger influence (rain, headwinds, winter gas, average speed).
Certainly not enough for me to worry about. |
Originally Posted by woof
(Post 1403318)
Winter gas is formulated to be more volatile so it vaporizes more easily in cold temperatures to help start your car. This added volatility is removed in summer gas because the gas would lose too much in the way of fumes and vapors in the warm temperatures adding to local pollution levels. And yes, summer gas gives slightly better gas mileage.
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