Currently have a lifetime of 55.6 mpg in my crx which came to $197.81 over EPA.
But what I have been doing to see how much money I'm saving is I'm counting how many mpg's I'm over my last car (civic) which was 35.6 mpg lifetime and that makes me $261.75 over my civic.
My initial plan for my CRX was have the gas savings put me into the +++ but I've put a lot of money into the car for things like registration, smog, battery/alt, ignition, muffler, and other miscellaneous things. Having an Excel spreadsheet for this helped tremendously.
As of now I'm 1133.26 in the negative in '14 (except for one '15 tank) for a fun driving car/project that keeps me entertained in my down time