I haven't done much highway hypermiling. In the city, it is relatively easy for me to get in the 40s after sustaining the warm-up hit. My current tank is at 40.0 mpg after 250+ miles according to the display. My favorite fuel economy commute gets me in the mid 40s. Here are links to a picture of the second half of this commute.

http://www.greenhybrid.com/share/sho...hp?i=2543&c=22

So far, my best tank was 37.3 mpg according to the display. It was actually my first tank as well. My current tank should become my new best.

http://www.greenhybrid.com/share/sho...hp?i=2515&c=22

Of course, this has mostly been in nice weather. An engine block heater will help minimize the winter mpg hit. I already have that and will hopefully install it this weekend.

For my driving conditions, I think hypermiling the HiHy is a little bit more relaxing than hypermiling the HCH II. Doing what is basically the equivalent of an FAS in the HCH II is as simple as letting the engine shut off and shifting to neutral in the HiHy. Basically, I just take advantage of the terrain to glide in neutral with the engine off as much as possible. I think the HSD in the HiHy is very similar to the HSD in the Prius II, so you can get tips from Prius II hypermiling articles. It will be interesting to see what kind of improvements the 2008 HiHy has in the way of the HSD.

As for interstate driving with cruise, I found the fuel economy to be slightly better than the 2005 Honda Odyssey minivan it replaced. I described that comparison over at CleanMPG in the daily grind thread.

http://www.cleanmpg.com/forums/showp...&postcount=114

You can click on my icon in my signature to see all of my tank data. I have decent descriptions of each tank.

(This is getting a bit off topic...) Also, I have found my odometer to be quite a bit off. I spent a fair amount of time to calibrate it. It turns out my odometer has to be increased by 3.4% to be accurate. Of course this is good for warranty purposes so I am not interested in getting it fixed. However, I use the calibrated numbers to calculate my fuel economy in the database. Anyway, the bottom line is that, at the end of the tank, the display fuel economy is extremely accurate. However, the miles driven is off. I detailed this over at cleanmpg as well.

http://www.cleanmpg.com/forums/fuel-...eter-5005.html