We know the best thing to keep mpg up is to not use the A/C.

We also know that above about 45 mph, the drag on the car decreases the mpg about as much as running the A/C does.

So what to do when driving on the highway (at 55 - 65 mph) on sunny days with temperatures above 95F? Opening the windows decreases mpg and does nothing to cool the driver. Running the A/C decreases the mpg and does cool the driver. What strategy should be used while running the A/C to maximize the comfort of the driver and minimize the decrease in mpg?

For instance, would a "pulse and glide" kind of idea work, that is run the A/C and fan on "max", recycled mode for a few minutes, then turn the A/C off with the fan on max. Or is it better to run the A/C set to some intermediate temperature and the fan on a medium speed and just leave it on?

What say you all?

 

I just crank it.. then when it cools off I have it running on medium low.. mpg be damned.. I'm not arriving at my destination all sweaty and smelly.

 

I have always thought that turning the A/C on and off would hurt the compressor. I may be wrong, but for that reason I try to avoid it. Usually what I do is run the A/C only when I am on a main road or highway. If I am on neighborhood streets that have many stop signs I try to roll with my windows down. Like you said, 45+ decreases gas mpg anyways so just run it on a main street.

 

It's best to:
Leave the Air Conditioning off...

that's my strategy. Unless, of course, my wife is in the car - then it's on full blast.

 

same here

 

AC off, windows up, cold drink in hand.

 

Why is it that women can't tuff it out??? My wife is the same way, A/C on.

I will run just the fan on the 2 setting(no A/C) and crack the windows every now and then to get it a little cooler.

 

Fans and window cracking doesn't make it any cooler when it's 100 F outside.

 

Turning the AC off and on won't hurt anything.
The compressor does that anyway as your driving.
It will kick in and out depending on the pressure.

 

I never use the AC around town, just keep the windows rolled down.

On the highway I have Mugen vented visors which allow the windows to be cracked without too much noise. I usually avoid using AC until it gets unbearable.... after that point I shut the windows and crank it! I use some techniques like turning it off on huge hills and when extra passing power is needed. Seems to impact my mileage by a couple of MPG at worst.

 

same here ac is only on when its beyond hot. other then that ac is off and windows are all the way down.

 

FULL BLAST the AC on stop lights and during idling where engine speed is lowest. Idling only burns gas and pump oils, but if A/C is on, a fraction of that wasted energy goes to A/C without sacrificing great amount of energy because you're not going anywhere while burning that fuel anyways. Also, you're suppose to loose horsepower as compensation for the A/C, but you're not going anywhere while idling, so you loose horsepower to regain fuel efficency, which doesn't matter because you don't need any extra horsepower to sit at a traffic light.

 

Thanks for the discussion about what A/C does and how best to use it.

For those who "never use A/C unless it's unbearable", the question was how best to use A/C when it is unbearable.

 

just turn it on and leave it on like me lol.

to me:
Comfort > an MPG or two

 

Get tints... you'll use the A/C less.

 

It's hot in Texas and I use A/C. Period. lol

 

Does tint even make a differance? If it is a dark tint it is still absorbing heat... unless you do a mirror tint I can't see it make a huge impact on cabin temps.

 

A/C is for WIMPS!



Just kidding!

After this tank, the A/C will be on. I am getting tired of having the wet seat belt mark across my shirt when I get home.

 

It makes a huge difference, whether it's reflective or not. I'm not 100% sure on how it works, but I'm assuming since the windows are now absorbing the heat, it's not penetrating into the car and onto the seats, floors, and, if you use a windshield shade, the dashboard.

Also if you can't afford tint then just get a windshield shade, it keeps the dash cooler, the A/C seems to get colder faster, and that means less time the A/C has to be on.

Personally, I'd rather get 30mpg and be cool than 36mpg and be sweaty.

 

Window film makes a huge difference because it stops 99.9 or so UVA and UVB rays. Those rays heat all the interior parts in your car to scorching levels. Those interior parts then heat the air in the cabin. Even in direct sunlight my steering wheel is not hot due to the tint.