AC and fuel economy

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Obviously, the compressor puts a load on the engine and fuel economy will suffer as a result. But by how much, what is considered "reasonable"? Since the start of summer, and 120 F temperatures, I've been using my AC continuously. My AC has an economy setting, where the compressor only works when needed, and an full setting where the compressor works all the time. Prior to summer, my fuel economy was 13.4 L/100 KM (17.6 MPG) with the AC running in economy mode. Now that I'm using my AC in full mode, fuel economy has dropped to 14.7 L/100 KM (16 MPG). My driving habits and routes have not changed. I find this rather reasonable, but a technician I was talking to said that's too "high". Am I right in thinking this is an acceptable figure, or is the tech right?
 
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I think its very reasonable. I get 8.5-8.6l/100km without the a/c and get 9.4l/100km with the a/c on with my cadillac cts on highway driving. total economy on the car (highway and city driving) without a/c: 10.2l/100km with a/c: 11.3/100km
 
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I noticed that my car's fuel economy changes very little on long highway trips with or without the AC. The best I got without the AC was 6.0 L/100 KM and with A/C on the best was 6.1 L. It was not on the same trip, but the results were very similar on other trips as well when I used AC. So for long trips I always use AC. City mileage in the other hand suffers greatly with AC being used. My work commute (80/20 City/Highway)avreages 7.8L without AC and about 8.5 with AC. However my car has a 2,0 I4 engine, I always thought that a bigger engine would not show much difference with AC on or off due to more torque, but I guess it still makes a difference.
 
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minneapolis mn
I believe the 120 air temperature has something to do with the mileage loss as well as running the a/c. There are few areas of the USA that reach those temperatures. Perhaps some one from the SW could chime in with their experience, In my own truck Chev S 10 with a 2.2 driven around the Minneapolis,MN USA metro area i lose aprox 1/2 to 3/4 mpg with the a/c on
 
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All depends on the hp to weight ratio or something to that affect. On the Escape the ac makes no difference in mpg city or highway. But the 3.0L duratec puts out over 200 hp. On the Ranger with only 150ish hp it doesn't affect the mileage much on the highway but the city is a different story. And you can feel the pull of the compressor on the Ranger not so with the Escape.
 
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ON, Canada eh?
My A/C only increases my fuel consumption by 0.5-1.0 L/100KM at most. As confirmed by my scan gauge. I think this is a reasonable trade off for my comfort!
 
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Da Swamp
I've always expected to lose about 10% of my regular average gas mileage when I have to run the A/C (which is far too much of the year here in The Swamp). However, on my last few fillups I've seen only about a 5% reduction from what I usually get: usually 22 mpg in 75% city driving; expected 20, got 21. It may have to do with the fact that I do my best to park the car in shade, put up reflecting sun shades, and blow the hot air out before I turn on the A/C, so it doesn't need to work as hard for as long. Also, as Eric mentioned, my car has about 200 hp, and the A/C doesn't load it down the way it would a smaller engine.
 
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los angeles
 Originally Posted By: Falcon_LS
Obviously, the compressor puts a load on the engine and fuel economy will suffer as a result. But by how much, what is considered "reasonable"? Since the start of summer, and 120 F temperatures, I've been using my AC continuously. My AC has an economy setting, where the compressor only works when needed, and an full setting where the compressor works all the time. Prior to summer, my fuel economy was 13.4 L/100 KM (17.6 MPG) with the AC running in economy mode. Now that I'm using my AC in full mode, fuel economy has dropped to 14.7 L/100 KM (16 MPG). My driving habits and routes have not changed.
I notice you put Kuwait as your location. Can you tint windows there? That might help some.
 
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I keep long term (5,000 mile +) fuel consumption records on my Mazda CX7 . In summer, with AC on 90% I achieve 20.78 mpg and in fall, winter with 0% AC, I acheieve 21.98 mpg. Delta = 1.2 mpg in Cape Coral, FL.
 
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 Originally Posted By: tig1
One to two MPG loss with the AC on. Average.
Thats the exact same thing with our 2 Crown Vics and Grand Marquis..We keep the A/C on automatic 100% of the time..My friend has a 03 Marquis so he gains 1 to 2 miles more as he does not like A/C but he spends a ton of money fixing window motors and etc since he plays with his windows so often.
 
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CROWNVIC4LIFE, My son lives in Gainesville, Fl. and drives a 04 F150, and 06 Expedition and their AC gets worked overtime. Much more so in Miami.
 
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ON, Canada eh?
 Originally Posted By: daves66nova
 Originally Posted By: Falcon_LS
Obviously, the compressor puts a load on the engine and fuel economy will suffer as a result. But by how much, what is considered "reasonable"? Since the start of summer, and 120 F temperatures, I've been using my AC continuously. My AC has an economy setting, where the compressor only works when needed, and an full setting where the compressor works all the time. Prior to summer, my fuel economy was 13.4 L/100 KM (17.6 MPG) with the AC running in economy mode. Now that I'm using my AC in full mode, fuel economy has dropped to 14.7 L/100 KM (16 MPG). My driving habits and routes have not changed.
I notice you put Kuwait as your location. Can you tint windows there? That might help some.
Falcon_LS and I are friends, his windows are tinted and I got mine done with my recent detailing to cut down on the heat after talking about Kuwait heat with him.
 
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 Originally Posted By: StevieC
 Originally Posted By: daves66nova
[quote=Falcon_LS]
Falcon_LS and I are friends, his windows are tinted and I got mine done with my recent detailing to cut down on the heat after talking about Kuwait heat with him.
Our whole fleet has 15% tint all around and dark strip on top of the windsheild..Plus we use a sun sheild..All that really helps.
 
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NJ
The show Mythbusters looked into this. It was not overly scientific but their findings were driving on the highway with AC will get you better MPG then if you had the windows down. The drag created by the windows was greater then the impact of the AC. Of course there are many variables but at 120 degrees I think they are your only options. ~1 MPG depending on habits is reasonable. It might even be less. I agree with the other poster that the high temps probably plays more into the decrease then the AC.
 

Falcon_LS

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Thanks very much for the input! \:\! Quite an interesting read actually, and I'm glad fuel economy is considered reasonable by others.
 Originally Posted By: StevieC
 Originally Posted By: daves66nova
I notice you put Kuwait as your location. Can you tint windows there? That might help some.
Falcon_LS and I are friends, his windows are tinted and I got mine done with my recent detailing to cut down on the heat after talking about Kuwait heat with him.
Yup, I've actually got solar tint on my windows, which does help a lot. \:\!
 
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Illinois
 Originally Posted By: Cardinal49
The show Mythbusters looked into this. It was not overly scientific but their findings were driving on the highway with AC will get you better MPG then if you had the windows down. The drag created by the windows was greater then the impact of the AC. Of course there are many variables but at 120 degrees I think they are your only options. ~1 MPG depending on habits is reasonable. It might even be less. I agree with the other poster that the high temps probably plays more into the decrease then the AC.
I saw that show as well and you have it just backwards. Better MPG with windows down and AC off.
 
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 Originally Posted By: tig1
CROWNVIC4LIFE, My son lives in Gainesville, Fl. and drives a 04 F150, and 06 Expedition and their AC gets worked overtime. Much more so in Miami.
A couple of years ago I went though Gainesville in August [I-75] coming from Kentucky and admit it was really hot..Its no fun outside anywhere in Florida in the summer.
 
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Nokesville, VA
 Originally Posted By: tig1
I saw that show as well and you have it just backwards. Better MPG with windows down and AC off.
They used either an Expedition or an Explorer as the test vehicle. I wonder if the results would have been different with a more aerodynamic vehicle. Rolling down the windows on those vehicles probably can't make what's already pretty bad that much worse.
 
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