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Fuel economy using A/C

5757 Views 16 Replies 9 Participants Last post by  iAoperator
Hello, I live in el Centro, California, you know, very hot summers. I need to have my A/C always turned on and I have noticed that my fuel economy has dropped significantly using the A/C.

I was getting up to 40 mpg without the Air conditioner on, and now it has dropped to about 25-28 mpg, ( i try to be gentle with the acceleration, and i normally drive it in the city, almost no highway).

Has anyone been using your scion IA with the AC always on? It would be great if you could share your MPG. :)
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been fine LA area.
It definitely isn't an efficient a/c system, but I haven't seen numbers that low.
Yes. I think it's pretty low. That's why I would like to know if someone could share their mpg using a/c to have something to compare my numbers and see if there's something wrong with my car.
It definitely isn't an efficient a/c system, but I haven't seen numbers that low.
what's consider a efficient A/C system :|
The color of your car could play a role in this. Black cars with small engines operating in extreme temperatures are subject to more operating pressure. Like wearing all black while under 120 degree weather. Not good mang.
Yeah I read about the color of the car, thats why I have the silver color IA, so it shouldnt be the problem.

Maybe as Jin said, it is an inefficient AC system :S
Well then.... Guys, its simple simple physics, NOT (an inefficient AC system ) as one member has suggested . A big part is: Its Load/HP ratio, look it up, not a difficult concept to understand, just a few paragraphs of reading. Jpdbasher's fuel economy loss is a combination of a lot of factors, Load/HP Ratio, Color, Temperature, Traffic, Speed, Weight of the Foot, topology, etc. Good luck blaming it on the vehicle, you won't get anywhere...... Not something any of us wants to see but it is reasonable.
Down the highway about 75-80mph, I turned on the "current mpg" thing, and with ac I had 38-43, with out I was about 60MPG
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Thanks tegwin. i will compare your Numbers wth my car. It is a very considerable difference in mpg in yours too!!
Ok so after a full tank these are my numbers:

Range: 273 miles. AVG Mpg: 27.3

Made this test with Ac always on and almost 90% city driving. No hard acceleration, no sport mode.
Down the highway about 75-80mph, I turned on the "current mpg" thing, and with ac I had 38-43, with out I was about 60MPG
100hp limitations
Is yours manual or stick-shift? Mine is stick, and the key is to not rev it more than 2000 rpm. I've noticed this too with my car and have been getting 32 mpg. But recently i went back to driving mostly highway and it went-up to ~39. I did discover a nail in my tire i had to take care of. Make sure your tires are properly inflated but not overinflated during the summer. I live in hot Arizona and it gets up to 117-120 degrees here in the summer. Brake Masters recharged my A/C two years ago when i got the car and it only blows cold when im driving 40mph or more.

Keep in mind that warm air is less dense and therefore has less oxygen for combustion and therefore lower gas mileage.

But my friend's Toyota and Honda blows cold nearly instantly after turning on the car and despite having black color paint.

Make sure your alignment is good, tires are rotated and balanced, back side of air filters are clean, that you change the oil every 4-5000 or minimum twice a year as it says in the manual or thrice a year for severe conditions. Any small bump will throw this car outta alignment, and make sure suspension is intack and has no blown struts.
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Interesting I did notice my MPG go down into the 20s (29.7mpg) for the first time I do be using my a/c alot and idle for extended periods of time . Usually I get 32 mpg combined with mostly city(suburbs)
I'm doing 41mpg ac or no ac
change oil and air filter according mazda specs
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