Since March 5, 2008 I've been keeping fuel and mileage records of my used 96 V6 Mustang. I've only kept records of complete fill ups; no way to calculate MPG with incomplete fill ups. But since 11-6-08 I've had continuous records. My overall MPG is 20.438, year 2008 was 20.624, 2009 was 20.804, and 2010 was 19.398. My highest was 27.942 MPG, with ~89% highway miles. Lowest was 15.46 MPG. And four different graphs to visualize my data.