Normally my instantaneous mpg gauge will vary between about 35 and 50 mpg at about 60 mph with the A/C on (ECO mode). After the car cooled off I decided to shut the A/C and leave the windows up to find out what difference I would get in mileage. I would say it increased the mileage by 5 mpg, now hovering between 45 and 55 mpg. I only did this test for about 4 or 5 minutes since it was getting pretty warm (no I'm not going to drive with a bucket of ice water and a washcloth).

I have the non-NAV Camry so I could only go by the instantaneous mpg gauge. It would be interesting for those with the NAV system's minute by minute mileage gauge to do the same.

Anyhow, I'm looking forward to seeing what mileage I get in the fall when I can shut the A/C.

 

I use the air conditioning full blast on a hill just outside of work on my commute home. That lasts to the next hill. Etc, etc. etc.

 

Hot summer days around these parts means 85 F. I usually don't use A/C as long as the air is dry but lately the air has been very humid. I don't have hardly any experience using A/C at highways speeds, but over the last couple of days I've noticed it takes quite a bit more attention to get the car to go into E-mode when the A/C (in ECO) on. In spots where I often cruise for long stretches in E-mode I've found the car will start the ICE even though SoC is not low. At times when I encourage E-mode by backing off the pedal, reapplying the pedal will start the ICE again. Sometimes a second attempt will keep it in E-mode. It will also turn on the ICE sooner when beginning up a gradual hill. I notice a significant FE loss in my commute as I'm not able to get as much of my infinite mpg fix, which I rely on greatly to balance portions of my commute that are FE poor.

 

Droid, very interesting. In southeast Virginia it's pretty hot and muggy. Rarely do we not make it into the 90s, so I've had the A/C on most of the time. I have also noticed that sometimes EV mode is difficult to enter and giving a little gas kicks on the ICE, especially in the 35-40 mph range. Perhaps that means I'll find it easier when the weather cools off in 2 - 3 months.

 

Out at lunch again today and found the same thing, as you say in the 35-40mph range. It really gets mediocre FE at this speed with the ICE running so I said screw it and jumped it up to 50/55mph (fortunately its one of those uncongested 40mph roads where most people drive it limit + 10 often). Got really good FE at this speed. I would hazard a guess that the A/C does not have a big impact in situations where the ICE would normally run anyway, but is a real killer at 35-40mph as it really does make getting a good E-mode run a pain in the rear. Doing the 25mph and below E-mode where appropriate seems to work the same with or without A/C. I think I've added a new strategy to my hybrid driving style, when in A/C if the option is available 50mph is going to do better FE for me than 40 does. Opposite when A/C is off.

 

I found the same thing. I keep it in the 40 - 50 mph range as little as possible. Not very efficient. This may get ridiculous, but I know in my trip when I can get a good 35-40 mph run. In that case crank the A/C ahead of time and then shut it for a few minutes so I can have an easier time doing EV. You are right about it being a pain in the butt. You ease off the gas to go to EV and then start increasing the pedal pressure. The speed keeps dropping, you keep giving more gas and then the next thing you know the ICE has kicked in.

 

If the ICE does not power the TCH's (electric) air conditioning compressor, how does running it affect MPG?

Do the post above suggest that the ICE is running more to recharcge the HSD's battery?

Any clarification will be appreciated.

 

It could be that the drain on the batteries does not leave enough left over to propel the car when you're in the 35-40 mph range. Just a guess.

 

I suspect what we are talking about is not necessarily an issue with charging the battery because it's low, but moreso some extra built in logic in the computer that decides E-mode at this speed coupled with A/C often not a good idea because either:

* draws too much power
* less efficient that running ICE overall
* arbitrary limit set by Toyota engineers
* prevents something bad happening
* insert your own idea here...