Jason,
I fully understand the difficulity of getting a good looking graphy. (The graphs on the website are great. I like them so much I pulled down a british Prius owners spreadsheet and have been copying and pasting my data in (Its easier for me to modify his charts than make my own). I find it quite interesting to see the current vs lifetime mpg values plotted. As well as the upward trend on the lmpg. Unfortunately with 4 years of data it is best to look at them one at a time or other wise the chart needs to be wider to see the trends. Have fun, RIck