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How many MPGs do you loose when running AC?

LYKOS

LYKOS

NAXJA Forum User
Location
Bent Mountain Va
My mileage has been all over the place this summer. And it's the first summer I've had AC in a few years.

Right now I'm bouncing between 14.5 and 16.5 uncorrected.

These are measured at fillup with no real change in driving habits. All fill ups at the same gas station etc etc. (I'm trying to avoid all the "you don't know how to check your gas mileage" answers. LOL

I know how to check gas mileage.


The only thing I can think of is that with the weather getting cooler I'm running the ac occasionally and that might be affecting MPGs.

I can't really compare to earlier mileages because of the front end trouble I've been having.


If not the AC what would cause your MPG to fluctuate so wildly? Bad sensor?
 
2-4 mpg is what I normally see my mileage drop when I run the AC.

That's over a week or two of regular use-- something I try to avoid, due to the expense of using it!!
 
AC sucks roughly 15 hp, so it is going to hit your mpg pretty hard.
 
A couple years back Myth Busters did this exact same test and believe it or not they came up with that with the A/C on and windows up it got better mpg than with the windows down and the A/C off.

Don't remeber exactly when or if I would believe them.
 
Depends on the vehicle. I know that PT Cruisers are like parachutes when the windows are down.
 
When my ac worked I didn't see a difference on the highway, compared to windows down I got relatively the same. I figured drag on the motor vs. wind drag ends up being pretty damn close.

Around town though I would see a difference maybe two mpg.
 
Mythbusters used two Ford SUVs; Exploders or Expeditions? Big with a decently sized engine. I doubt that running the AC with the windows up is more efficient for all cars.

I don't see a difference on the interstate, or really even on the highway, but I do lose a few mpg in city driving.

2mpg could be any number of things. Traffic, construction, running the AC, needing a tuneup, wind... I don't get worried until the mileage falls and stays consistently low.
 
I actually get a little better gas mileage, or break even at worst, running my AC, as it makes the coolant a littler hotter, engine a little hotter, and so the engine runs a little more efficiently on mine.

I have 180 T-states in mine, in Houston.....

87 and 89 Renix, 4.0s
 
You will, in fact, get better mileage on the highway with the windows up and the AC on than widows open and the AC off. I have seen this on every car I have ever owned. The added wind resistance with the windows down requires more Hp than the compressor.

Around town, you will just lose with the Ac on. No advantage at all...
 
Loose? None.

Lose? Don't know, don't care. If I was worried about gas mileage, I'd be driving something besides a box on wheels.
 
MT Mike said:
Loose? None.

Lose? Don't know, don't care. If I was worried about gas mileage, I'd be driving something besides a box on wheels.
Click to expand...

I worry about it. The type of trips I go on quite often puts me in situations where I have to carry more fuel.

If I could get 15 mpg instead of 13 it would net me 40 more miles of range. That's significant.
 
MT Mike said:
Loose? None.

Lose? Don't know, don't care. If I was worried about gas mileage, I'd be driving something besides a box on wheels.
Click to expand...

I'm more than a little lazy on spell check. Specially on Tapatalk.

It's my DD. The difference between 13 and 16 adds up to MONEY over the course of a year.
 
MT Mike said:
Loose? None.

Lose? Don't know, don't care. If I was worried about gas mileage, I'd be driving something besides a box on wheels.
Click to expand...

Box or not it is easy to reach 34 mpg with a Cherokee.:eyes:

You just have to think outside the BOX!!!! LOL

I do it routinely with one of my DDs. My 1985 Cherokee Pioneer gets me about 34 MPG, with the AC running.:greensmok
 
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