I have stopped the majority of my hypermiling techniques because, frankly, it was too much of a pain. As such, my milage has dropped a bit. Some of it is due to the cold weather and fuel changes, I'm sure, but I'm getting around 45-47 now, and I was getting 49-51 when I was worrying about it. It might all be the cold, but I really haven't concentrated on FE for some time.

That said, my worst tank has been 44+ mpg. I did have one stretch where I was getting 29mpg, but that was in freezing weather on super steep hills (suburban Pittsburgh) in massive stop and go traffic jams. Those three things are the three worst-case scenarios and I still got 29, so 28 in normal driving sounds very odd.

I have about 600 miles and my best trip was 52 mpg. Some city driving but mostly freeway, with some stop n go.

Keep your rpm's below 3000 on the uphill, even if that let's you drift down to 55mph. By doing so, I regain my losses on the downhill portion. 5500 miles on mine in 26 days, no tank less than 41 mpg, and 1 tank over 51 mpg. I work hard at it, though