I was looking over the milage database and noticed that all of the HCHII's which had mpg numbers > 46 are from southerly areas (with West Virginia being the farthest north). The lowest mpg values are from relatively low mile cars in the north (Canada, Chicago, Minnesota), with the exception of CGamePRogrammer who is in San Diego. Just thought this was an interesting observation.

DKeane

It's the temperature. Temperature has a lot to do with mileage. Also, a lot of nothern places have reformulated gas in the winter which drops the FE by a few points. My MPG drops around 10mpg in the winter vs the summer.

My hydroponics experiment

You ever notice how hard it is to lip read cartoon characters?
"Crazy is what the sane call Delta Flyer"

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Just as a reference for what decent weather can do for you, I live in Southern
Florida where the temps have been in the 70's without reformulated fuel.
I picked up my 2006 HCH on Tuesday and have avg. 52 mpg for 200 miles (40 mile trips).
The mpg reading is per the digital indicator haven't completed a tank for manual comparison yet.

Mostly highway driving (heavy traffic in evening commute), and some city.
Some small hills on the highway but for the most part flat.