All,

This is my personal spreadsheet that I have been using to keep track of all my CNG fillups since I purchased my Cavalier back in June 2007. I also have been plotting out the "complete fillups" at the Ogden and Clearfield stations and using a statistical aid called cusum (cumulative sum). This gives a graphical view of the fillups compared to the average fillup. As you can see from my spreadsheet when compared to a vehicle that gets 40 MPG on gasoline I have saved over $700. This also assumes that I only get 27 MPGGE on CNG. The fillups in tan color are my fillups with gasoline.
Attached Files