does i lose more gas when my a/c is on? is that true?

 

Yes, it use the engine more. You can tell in the RPMs when idle.

 

I read an article several years ago concerning the economics of using the airconditioner. The article stated that compared to driving with the windows down the A/C was more economic because of the increaded drag on the vehicle caused by open windows.

 

Again, the fact is, yes, it uses gas. However, the benefit of big trucks with large engines like ours (as opposed to most passenger cars) the difference is negligable. I'd be surprised if you noticed anything more than a tenth of a mile per gal lost. Woo hoo!

 

While I am not exactly sure how much mpg you lose with the AC on, I'm convinced it's more than a tenth. I think it's hard to measure since when it's hot out your loosing hp thus compensating with more throttle. Add A/C into the mix and I don't think loosing 1mpg is all that unbelieable.

 

I've read where AC uses 10 to maybe 12 hp max. On a 260 HP engine this isn't much (like our trucks). On a small car (Miata with 106 hp, you really feel the hit). Point is, taking aerodynamic drag and all other things into account, it is such a small percentage that under highway conditions, it won't matter much. If you are totally around town, the HP requirements will be a higher percentage as you are not generating much HP at idle or low speeds. I'd say it depends but I know I'm sure as he}} not going to do without down here in Florida. Your choice. You can't study it very well because to get accurate MPG figures it requires many miles and then averaging the results. Conditions change during the day and from day to day so you can't really quantify the results to well, too many variable change in the experiment.

 

yes but you're not using all 260 HP when you are cruising down the road. you're using a small portion of that. 10 to 12 HP is a much higher percentage if you are using 100 HP or less. my guess is that AC costs about 1 to 1.5 mpg if my mileage is any gauge. i was getting 19 before i needed the AC and now i'm lucky to get 18. call it a hot weather penalty not unlike the cold weather penalty. i'm NOT saying that running AC costs more than running with the windows down.

 

What engine do you have? I wish I was getting 18/19 mpg. Im lucky to see 15 with city driving and I have the 4.6L.....

 

I usually notice around a 1 MPG difference between the winter and summer (when I'm useing the A/C.) The difference in power though is considerably more. I'd *guess* you loose atleast 10% to 15%, although in Texas I'll gladly give it up!

 

Yes.

You also pay for the weight of that comfy seat, the power windows, extra height (like pulling a kite) of the truck, wind drag of the tailgate, and the extra weight of the truck alone.

But, aside from an engineering debate, what's the point?

 

Yep, there is a penalty, though I would peg it at 1mpg or less (more like 0.5mpg). With the availible power of these engines in our trucks, we can power the AC without the penalty being too noticeable. On my '89 Cavalier, I notice a 3-4mpg loss when running with the AC on. Of course, peak HP is only 96 HP anyways, so the AC is a huge deal to the engine. I also remember the same study that said driving with the windows down vs AC - the AC wins. Too much drag from the wind entering the vehicle with the windows down.

 

I've been averaging about 14.5 mpg since I bought the truck. In the summer with the A/C on in city driving I get in the low 13s and sometimes the high 12s. 1 to 1.5 mpg might not seem like much, but it's about a 10% loss.

 

Yeah it does affect it somewhat. I don't use mine very often, but when I do, I notice on take off the engine is a little more sluggish and takes a higher rpm to get it up to speed. It doesn't help that I love to here my exhaust sing. Ever since then my foot has gotten much heavier. Hmmm, I'm sure some guys can back me up on that one.

 

It seems that with the AC I lose about 1 to 1.5 mph but then I have a bit of the problem of bennett399 in that with a flowmaster and K & N I like to hear the sweet sound of the pipes so I could be part of the problem. In town when I am a good boy I get around 14mpg.

2000 F150 super cab
5.4
3.55
trailer package with out the correct radiator
flowmaster
K&N soon to add the homemade cold air induction
Island Blue
CD

 

I believe A/C will affect gas mileage 1/2 mpg to 3 mpg depending on the car.

All I know for a fact is, on a 2001 BMW 325i manual at 3500 rpm, on a level road, it worsens it by 1 mpg (+/- 0.2 mpg.)