I thought about sticking this in my beloved HCH forum but it's universal really, and besides - I'd like to see the disparities between 1) make/model and 2) location. Basically I'd like to throw in an informal category of $/mile driven for your vehicle. Insights should come out pretty but then again a Prius in southern GA would be tough to beat. I've kept a log since purchasing my 2005 HCH in April, with the price of each fill up as one of my columns. This is how it looks to date:
TRIP @ $ = $/MILE
409.2 $23.00 $.056
428.9 $21.00 $.049
430.3 $19.00 $.044
432.2 $18.50 $.043
392.4 $18.64 $.048
502.8 $22.24 $.044
430.0 $23.26 $.054
483.7 $23.28 $.048
526.0 $27.07 $.051
658.7 $33.24 $.050
432.3 $23.97 $.055
5126.8 $253.20 $.049 = LIFETIME
Price per gallon plays a substantial role in this; my best tank of 58.0 MPG actually cost me a nickel per mile driven, where my car's early life spent in the low to mid 40 MPG range generally was about 4.5 cents.
In an accompanying post, I'll add my entire Word Spreadsheet of the car's vitals thus far, which includes date filled and price per gallon.
For those of you fellow nerds

who keep track of this stuff, PLEASE try to add as much ongoing info as you've got time for. I'm very interested to see how my HCH in Florida stacks up to a Prius or Insight in more expensive areas, or an FEH or HighHy in cheaper zones.