A/C affect on Milage

If you are comfortable at that setting, so be it.
I run mine in "Auto" at 70F.

 

on the highway, it's a wash. but on the back roads it can be anywhere between 2-5 mpg's, depending on the weather.

 

Its seems like cold weather and wet roads have more of an effect
on mpg than the AC, in my opinion.

Took a trip in the summer from Seaside Oregon to Reno Nevada and still averaged a calculated 50 mpg plus round trip, AC on nearly all the time.

In the winter here in Oregon my average is 46-48 mpg calculated, weather 35-50 degrees, wet rain soaked roads, and steady rain for nearly 6-8 months.

Now with temps in the mid 50's and dry roads last fillup was over 57 mpg calculated.

alfon

 

Prius an amazing vehicle. Had mine a 2011 III for only one month 1000 miles on odo drove 250 miles first short trip in the rain, with a/c on at 70 blower 2 bars and got just over 52 mpg. The only car i always get at least the govt. mpg rating but usually higher. AMAZED.....

 

Here is almost 7 years of data relating mpg to temperature. There is some impact from summer AC use, but cold weather has a larger impact.

 

that was my observation too.

At lower speeds you are better off with open windows, at ~55-65MPH running A/C at 78-80 with recirculation will have no impact on MPG. Provided you have to use brakes once in a while.

At higher speeds ECU keeps battery nearly fully charged, stopping from 60MPH on a red light will waste all regenerative energy.

 

oh ya, cold vetter is da vurst!

 

If you have the fan running, and the AC light is not on, is the AC not running? Or maybe not running? Is there any way to tell, to force it off, other than shutting the fan off completely?

 

not sure on the III, but on the II, there is an a/c button.

 

What I'm wondering: if the AC button is not expressly pressed, and there's no light showing on it, does that mean it's not running, for sure? I'm pretty sure if you've got the heat/vent. system in auto mode AC may be running regardless. But not really sure.

 

If you push the a/c button and it lights (green) a/c is on.

 

III the same

 

The only time that I have been aware that the AC was on, even though the AC button was off, is any time I have one of the defrost modes on. Either the front defrost or one of the modes that includes the front defrost mode. The unit uses the AC to help remove any moisture on the windshield.

 

Great record ! My experience without such detailled data is similar except terrain and speed also make an impact.

 

Yesterday I returned from a 5000 mile trip. The Prius performed flawlessly. It was 95-100 degrees in Texas ... A/C the entire time. No significant impact, other than being perfectly comfortable in the car.

Coming home we had a 30 mile/hour head wind. That hurt. Then when we turned north, a 30 mile/hour tail wind. My mileage went from 48 mpg to 56 mpg.

BTW, gasoline is much less costly in Texas .... even the name brand gas is lower cost.

 

Actually it just occurs to me, we were on the last leg of a long weekend road trip yesterday: Heat/Vent system in Auto mode, temp set to around 21 deg C, no AC button light showing, but for sure it was cooling, ie: AC running.

BTW: IMHO Toyota confuses matters by constantly referring to the Heat/Vent system in the Owners Manual as the "AC" system.

 

agreed! ^

 

Another thing to consider: if it is too hot the hybrid battery will overheat and will not be used to full extend or not at all. Under these conditions A/C would actually improve MPG.

 

Hello Ben! Well, my five month old Prius III has suffered along with me as our temps have surpassed 90 degrees. I bought it at Christmas time and was getting 50mpg Orlando local driving. A month ago it started downhill, and now I'm lucky to get 42mpg with carefull driving. We keep the A/C at 71 in auto. I have heard the same from two other new owners. I notice the battery charge state indication seems to take longer to go up, and never goes higher than about two bars from the top. I keep it in ECO mode, but traffic rarely permits me to keep it in the left portion of the ECO display. Needless to say, I am disappointed.

Ed