The last couple of tanks I have had have been less than outstanding. I am driving a little more in rush traffic (a couple of times a week) and also adding a couple of short trips with frequent stops (ie stopping at several security gates)to my weekly commute. My current tank started 1/2 through my normal commute home at 4:20. This puts me before the 5:00 rush but squarely into the naval station rush. I refilled after the downtown part of my commute and just before getting to the navy base traffic portion.

Here's what I found interesting: I had three stops over the remaining 9 to 10 mile commute. But inbetween I was able to do 50 to 55 miles per hour on cruise control. When I got home, my FE was at 40+. While I would think this was to be expected, since it is in the sweet spot for FE, I was suprised the 3 stops and accelerating back to speed would have cancelled out the great FE. As a comparison, on my comuute back to work this morning in similar traffic (maybe one more red light than yesterday), my FE fell to 31.5. There was a 20 degree difference in outside temperature (65 yesterday and 45 this morning) and the car was warmed up before starting the new tank yesterday. Other than that, no real differences in the commute.

Wow...going from 42 mpg to 31 mpg because some of the 20 minute commute was with a cold car and colder weather? I might start resetting my trip A during my commute to see what areas of my commute are the best and worse for FE. I never realized the difference was that great before.

BTW: I think the thing I hate about driving a HAH in heavy traffic is deciding how close to follow the car in front of you. Too close and you are at the whim of the guy in front of you and will experience heavier accelration and braking. Too far back and everyone zooms around you and fills that cushion zone you are trying to develop so you don't have to slam the brakes everytime the brake lights go on ahead of you.

I've seen similar FE changes. On a shortish drive (10 miles or so) just a few "small" differences do have a large effect. Even on my 33 mile morning commute, at 30deg I get 36ish mpg; at 40deg 39, at 50+ I am over 40. Initial conditions in those 1st 2 miles before I hit the highway play a dominant role, even with 30 highway miles to pad it.

I've seen similar. I live on a hill and the last quarter mile going home really dents my FE. And I can't get it back in the morning going down to the highway bec it's not warmed up yet. I thought maybe it was helping to FAS my way down the hill and warm up on the highway, but of course that doesn't balance out the loss on the way up. Haven't got an answer for gravity, at least as long as I insist on traveling around in a ton of metal.

Love my HAH.