It's hot out here in So Cal, and my car's working overtime. I like it cool in the car, so I have the A/C on constantly.

What type of mileage affects do you guys see with A/C?

I am losing 5%-10%. That's significant, even though I am not the hypermiler many here are. Typically I'll see around 40mpg. Sometimes more, sometimes less. Recently, I've been seeing 37ish. I was worried, so I checked tire pressure, etc.

To experience the effect of A/C on my car, I turned it off and on a couple of times while going up a slight grade on the freeway at 60 miles per hour. Big difference!

Anybody else notice changes?

Thanks,
Lansing

I lose 5 miles per gallon with AC.

This pic tells it like it is.....

Wow...then I don't feel as bad. I thought something might be wrong with the ride!!! Or worse...the driver!!!!

Thanks,
Lansing

I don't see much of a change when I use the AC, but I drive about 20-25 miles every time I get in the car. When I crank it up at first to cool the car, it does drop the milage, maybe by 0.4 or, if a light is long and I can't do autostop, 0.8. But I scale back the AC as I go until I'm running with the air on 70 degrees and lowest setting after Auto, and I make up the mpg difference. When I'm using the low settings and driving steadily on a flat freeway, I see no difference between having the AC on and having it off. I'm still getting my 48 mpg this tank.
--A

That's interesting. I myself see decreases and the biggest impact being when it's 100 degrees out and I am jumping into a hot car with AC on max until it cools down. That combined with short trips and stop/go have to be the culprits!!!

I will say one thing. I'm planning on going to Vegas for the 4th. I took the HCH last time, but think I'll take another car this time. It's so hot and the HCH AC is just mediocre in the desert heat.

Lansing

I don't see much of a difference, if anything, I see a net improvement in the summer, despite the AC usage, because of faster warmup time. The reason for that is because I already throw away a large portion of my gas mileage climbing the large hill to my home. On the way back down, the hill is too steep to be able to recover all the energy with regenerative braking. However, in the summer, I actually run the AC on max in recirc when coasting down, so the AC is powered with "free" energy that would otherwise be wasted on braking. By the time I reach the bottom, the car is so cold that only minimal AC is necessary to maintain 82 degrees for the rest of my trip.

Balancing the AC load to make it work harder when going downhill should be part of the "Econ" mode on the car by default -- it makes a big difference.

Lakedude,
Do you know the source of that chart?
Those CIVIC AC on numbers (35.5 MPG?) just look awfully low. Some folks here are claiming they see little difference in MPG - AC on OR off.

Steve

STOP terrorism - Drive a HYBRID

Vehicles:
350 miles a week ------------ 2006 HCH II, Magnetic Pearl, w/NAVI (born on May 25, 2006)
350 miles a month ---------- 2003 Mazda Tribute ES-V6
350 miles a year (for now) - 1986 Mercedes 560SL

http://www.hybridcars.com/air-conditioning-effects.html

Thanks. Interesting quick-read.

I noted this quote: "In lab tests, mileage data was collected with the air conditioning either completely off or cranked to the highest level. The hybrid fleet testing was conducted in locations throughout Arizona, representing a diverse range of climates and driving conditions."

So the test was - OFF or AC/MAX.
Maybe there's a more normal setting that results in less MPG dropoff? I think many people do NOT leave their AC on MAX all the time. Although in hot climates, like mine, it is more often than I'd like to admit!

Also noted this quote: "The testing also dispelled a persistent myth that the rechargeable batteries need to be frequently replaced. Francfort originally thought their battery evaluations would "go to 100,00 miles because that's how long the batteries are under warranty. The batteries were working so well, we thought we'd go further." They finally settled on 160,000 miles. Evaluations showed that the rechargeable batteries lasted to 160,000 miles with no effect on fuel economy."

This is good news (and as expected, on average)!

Steve

STOP terrorism - Drive a HYBRID

Vehicles:
350 miles a week ------------ 2006 HCH II, Magnetic Pearl, w/NAVI (born on May 25, 2006)
350 miles a month ---------- 2003 Mazda Tribute ES-V6
350 miles a year (for now) - 1986 Mercedes 560SL