Does running the air conditioner really reduce a car's gas mileage?

Question

This will settle a friendly bet between my wife and I. I say yes, she says no.

Answer 1

yes, 1 to 3 mpg, their is a 5 to 10 horsepower drag on the engine, try to spin that compressor by your self with a wrench with the engine off! sources, common sense. also most cars have electric fans that runs full time when air is on, that takes power from alternator , and the alternator pulls energy. also the car runs hotter so you lose efficiency. sources, husband mechanical engineer.

Answer 2

I've done some testing with this so I'd know if there was a "crossover" speed...

What I'm saying is that at lower speedsthe air-conditioner absolutely, definitely uses more gas. No question. The battle goes to highway speeds versus having the windows open. The air-conditioner compressor uses more gas no matter what. The windows use more gas as you increase speed; how much more?

What I tested with...www.scangauge.com I bought one of these to do my own myth busting...you can really learn what gives good mileage and what sucks the gas right out of the tailpipe with this thing. (Instant read out and you help calibrate it every time you fill-up and tell it how much gas you bought. When it already knows then it's calibrated.)

I've tried this on a 2004 Nissan Maxima (mid-sized) and a 2006 Honda Civic (compact) and it absolutely uses more gas with the air-conditioner than with windows down at ALL legal speeds. the Maxima found a crossover speed with extra drag at around 85 mph (don't ask me how I know that) and the Civic NEVER did. Of course I didn't go beyond 100 mph to prove the point. I'm sure that at some speed it would.

I really wanted to support the "she" in the "She said, He said" scenario but I'm afraid that the "He" is right this time.

Keep the bets friendly. PM me with any gas mileage or fuel economy questions.

Answer 3

A car air conditioner will take about 5 horsepower to run. You can feel the engine slow down when idling when the air con switches in. Yes, the engine has to drive the air con compressor through the vee belt and that takes power. The only way the engine can get power is from the gasoline, so the mileage gets a little worse.

Answer 4

Yes. I drove an older Ford Ranger truck for awhile that had a broken gas gage, so I filled up with gas when the mileage odometer reached like 300 miles. But if I ran the air conditioner, then I had to fill up a little sooner, as I learned when I ran out of gas and thought I had about 50 miles more to go. So, the answer is YES!

Answer 5

The skinny on this one is determined by the year of the car. In newer models the air conditioning system is so efficient, that it does not reduce the cars gas mileage. In fact, you get better gas mileage, with the a/c on, than if you had your windows open, which creates drag and less gas mileage. Older model are less efficient and do lower your gas mileage. So, not to cause an argument between your spouse and you. The answer is, not all the time, but sometimes...

Answer 6

actuality: Turning the compressor takes skill from the engine, ensuing in fairly decreased gas mileage. in the previous you commence rolling down the abode windows, there is yet another actuality to judge: taking off the abode windows outcomes the vehicle's aerodynamics, and could also shrink gas mileage. because they're both particularly a lot a wash gas mileage sensible, i go with to bypass with the cooler answer and crank on the A/C.

Answer 7

Yes it does, but if you have to drive highway speeds with the windows open on the premise that you're saving gas, you're really wasting it. Cars are meant to be aerodynamic, so opening the windows creates drag and wastes more gas than if you just ran the air. I would say that both of you are right this time on different levels. You both should call it a draw and take each other for a night out on this one.

Answer 8

Yes it does reduce gas mileage. However you won't gain that much by not using it and opening the windows because the drag it puts on the car will use gas also.

Answer 9

Not really anymore. Manufacturing processes have become very efficient and modern compressors just don't draw all that much off the engine. It has mostly to do with high-tech lubricants and the tolerances of the bearings being very exact. The added drag on the engine is roughly equivalent to the added drag of driving with the windows open, so you can blast that A/C without guilt.

Answer 10

Yes you will use more Gas the Air Conditioner makes the Engine work Harder thus using more fuel. You'll use more gas in the city than on the Highway. But you will use more Gas nonetheless.