http://biz.yahoo.com/cnnm/070515/050907_gas_myths.html?.v=1&.pf=family-home

Interesting read there. However, I myself have tested running the AC all the time and not using 1 drop of AC through a whole tank, and the difference is somewhere between 1-1.5 MPG. When not running the AC, I don't roll down my windows, but just turn on the fan.

Anyone else tried this before? Not sure my experiment is 100% valid because my MPG may have increased due to my car breaking in.

I don't let any articles tell me how to save gas, I don't care how expert they are. I am the expert of my own car, I get out and I do my own tests and determine what works.

Consider this, proponents of cutting down on greenhouse gases use an argument that goes along the lines of...well if it is really greenhouse gases and we cut down, then it's a good thing...even if it's not greenhouse gases and we cut down, it's no big deal. So what happens when you turn off the AC and don't roll the windows down? What the hell do you have to lose, maybe a little water weight from sweat? :lmao: You certainly not going to get WORSE fuel economy.

Turning on your AC during steady state highway driving is not going to significantly affect your fuel economy...know why? Your engine cruising at 2500RPM is producing more HP than it takes to move the car. If you turn on the AC, some of the extra power just goes into powering the compressor. When you climb a hill, or when you're starting out from a stop, accelerating in the city...that's when you need all your HP, and that's when you will notice the fuel economy take a bigger hit. Basically the same thing with your windows open, the extra drag requires a bit more power but your engine shouldn't be struggling to move the car, so the hit won't be big. Except in this case it won't affect you as much as AC in the city. And their little test only does highway numbers, so it's flawed

We had another thread about AC usage too
http://www.driveaccord.net/forums/showthread.php?t=11295

Another point (I made in that thread) the MPG you lose from AC can be made up by the temperature difference (ie. you wouldn't use AC in 55 degrees weather but the engine would use more fuel due to denser air, in 80 degree weather you use AC but less gas from less dense air)

So, A/C costs about 1k to add to a car (most come standard), but I'm not going to use it b/c it costs 1 MPG per year....

1 MPG Difference

15k miles a year/30MPG*3 dol/gal=1.5k per year for fuel

15k miles a year/29 MPG*3 dol/gal=1.551724k per year for fuel

Difference is $51.72 a year

That assumes you use it all year....I will use the crap out of my A/C if I want it......those savings just don't sway me enough to be uncomfortable...

Your sunroof and power windows also cost you $1K each, why don't you use those instead?

The argument that I have it and I can use it so I will makes no sense. Your computer cost $1K why don't you leave it on 24/7? How bout your TV? Your sink came with the house, why don't you leave the water running while you brush your teeth? It's absurd!

You are assuming a 1MPG difference. What if it's 2 or 3MPG? What if my car only gets 20MPG, the percentage gap grows. What if everybody were like you? 200 million cars out there in the USA, each one wastes on average $100 a year, do the math Mr. Engineer. How many barrels of oil is that?

A/C knocks 2 to 3 mpg off the Accord and Civic here mostly hwy. Use it in city traffic 3 to 5 mpg. I use the power windows feature more. :)

I like my windows and roof open too anyway. Its nice to have the AC when its hellish hot. But the mpg off isnt on my top list of worries. Yah it sucks, but if im sweating my arse off with the windows down, ill still use the AC.

cheers

Common sense dictates that if it gets uncomfortably hot in a car and you have air/con, then you should use it.

Does owning things you don't use make sense? no not really.. :dunno:

We can all help the planet far more by being carefull about what we buy, i.e. where it came from, than we can save in a lifetime of not using air/con in a car when conditions warrant it..

E.G. I used to use planes a lot to fly internally, because it was easier, quicker than going by road, I don't do that anymore. I used to own-drive huge cars that were very heavy fuel users, i cut that out too.. The good news is, I got more money to waste now.. lol.. :banana: :banana: :nuts: :lmao:
.

Jeez, did anyone actually read the article? :scratch: It's saying that it's okay to leave your windows down or AC on as you wish, as it will have "no significant difference."

I'm the one who tried going 2 separate tanks, one with all AC and one with no AC and just noted a difference. I was just asking if someone else had done this before... :dunno:

dust off your slide rule...

One gallon of gas has about 36 kilowatt-hours of energy in it. If we assume 25% net efficiency for a typical car, that makes 9 kW/h that you actually get to spend. A typical a/c compressor in a car will draw 4 kW/h at full load. So, if you are running your a/c at full tilt you will burn an extra gallon of gas every 2 hours or so. How much gas will you use to drive for 2 hours? Example case, you do 75 mi/hr and earn 30mpg, using 5 gallons of fuel. An extra gallon is 20% more! Do you run your a/c at full tilt the whole time? probably not, since modern compressors are variable displacement and only draw enough energy to provide a set pressure drop in the system.

Bottom line, the energy must come from somewhere, and how much you expect from your air conditioner will have an impact on your gas consumption, from negligible at a low duty cycle, to very noticeable at a higher duty.

Jeez, did anyone actually read the article? :scratch: It's saying that it's okay to leave your windows down or AC on as you wish, as it will have "no significant difference."

I'm the one who tried going 2 separate tanks, one with all AC and one with no AC and just noted a difference. I was just asking if someone else had done this before... :dunno:
I read the article and I'm saying it's inaccurate...their test conditions are slanted to show no difference and you can easily see why without even doing the test.

And you see we do have people who tried it, like psyshack.

since ive been living in florida, i've had to use my a/c most of the time due to the weather down here.

now that it's approaching summer, i will be pretty much using the a/c for the next 3 months at least non-stop. the only difference i've actually noticed with gas mileage when running the a/c is 1 mpg. thats ok for me since i dont drive much down here anyway. just to work and school.

my car is still breaking in anyway so im only getting about 20 mpg with mixed driving, but im starting to notice a slight increase every time i fill her up. i cant wait to get that crappy break-in oil out of there. only ~ 3,000 more miles till my first service on this car.

If you really want to improve your mileage, set up a pole protruding out from the front end, and place a large magnet on it. Your car will automaticaly pull towards the magnet, thus increasing your MPG. :thumbsup:

If you really want to improve your mileage, set up a pole protruding out from the front end, and place a large magnet on it. Your car will automaticaly pull towards the magnet, thus increasing your MPG. :thumbsup:

Good but I can do you one better...

Simply install a magnetic grapple on the front of your car, fire it at the nearest semi, then simply shift into neutral and kill the engine. Vola, infinite mileage (in whatever direction the truck is going). Just remember to brake when the truck brakes, otherwise the result won't be very pretty... :lmao:

Better yet, put really large tires on the back and small tires on the front. The forward slope will mean you're always going downhill and...bam! No fuel needed. You coast everywhere you go.

:yes:

It's great to see the creative thinking going on here! I didn't read the article but wanted to interject that 95% of the time my climate control is on automatic so I don't know which system is actually working at the moment. I do tend to set the temp setting to 75 after a few minutes when the recirc comes on after a day sitting in the sun at work. Otherwise the A/C works too well and blows cold air at me. Usually the temp setting is at 72. I repeatedly get 23.5 mpg or better in my daily driving to work and around town so I don't think getting home all wet from sweating like a hog nostril is worth turning the system off. I used to sweat in my Ford Ranger with leaky A/C hoses and that's why I bought the Accord. Not the main reason but a reason. :)

Jeez, did anyone actually read the article? :scratch: It's saying that it's okay to leave your windows down or AC on as you wish, as it will have "no significant difference."

Keyword, significant. Their version of significant and my version of significant could be vastly different.