I've been trying to determine how much of a hit you get with A/C. Part of my problem is my impatience. When I see the FE dropping, I tend to turn the A/C off. I always use ECO to minimize the hit and I only use it on the highway. Most of the time I don't even think about using it because it doesn't get that hot here. However, today, the temperature was really up there, 90F so I turned the A/C on. I quickly so a decrease in the tank average. It dropped 1 mpg and was still decreasing when I turned it off and opened the windows. By that time, the temperature had decreased to 86F outside.

My best guess is it drops mileage by 2 mpg.

I'm wondering what others have measured.

In case you're wondering, I like it hot and 85F doesn't bother me. Warmer than that and I plan to use A/C.

 

In my experience, opening the windows will cause a bigger hit than using using the A/C, at least at highway speeds.

 

I see a 2 to 3 mpg hit with the A/C running in ECO mode. Check out this thread: ECO A/C Mode impact on MPG

 

When it's hot, use the A/C - that is why you have it. I guess I don't worry about the 1-2 MPG hit, I'd rather keep myself and my family comfortable.

Scott

 

I thought that the A/C was electric, not powered by the ICE. If it is electric, why is there a drop in FE? I can understand if on short trips, if the SOC drops to purple, the ICE will run to charge the battery, but on the interstate, the ICE runs in conjunction with the battery powering the wheels while regen brakeing should charge the battery. So why a drop in FE?

 

Nyce: Think about it. Energy has to come from some place to run the AC, even if is electric, and the only place is from the ICE which burns gasoline, thus lower FE.

 

Because ultimately, all of the energy the car uses comes from gas. When driving on the highway with the ICE running, some of the energy will be powering the wheels, and some recharging the battery. With the A/C on, there is a bigger draw on the battery, requiring more energy from the ICE to keep the battery at the same level.

 

Idrove from central Illinois to central Mississippi. A total trip of 522 miles at 75 mph with the a/c on. 100+ outside temp. I averaged 42.6 mpg (measured) for the trip......if the a/c makes a hit, it is so minimal I don't care about it.......does that make me unworthy of being a hybrid owner?

 

Nope, just makes you a non-sweaty hybrid owner.

Scott

 

Likewise, which goes back to my earlier point that opening the windows is worse than using the A/C.