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.