Anybody have some REAL numbers for effect on mileage due to A/C use?
I noticed my last tank dropped about 2 mpg to around 31.5 for no apparent reason, and this tank looks to be even worse (computer currently reading about 30.5). This is after getting 33-34 over several tanks on my commute. The most likely culprit is increased A/C use - I used to use it only in the afternoon but started carpooling recently and I'm using A/C in the morning now too for the benefit of my passenger. But a 2-3mpg hit was much more than I was expecting.
The other main possibility is bad gas - I'll be switching stations next fill up to see if there's any effect.