but I've kept a spreadsheet of every tank of gas I've had through the 3 Z32s I've owned going back to July 1991 when gas was $1.219/gal. In that time, I've drive a total of 241,237 miles, used 13,759 gals for an average of 17.5 mpg at a total cost of $19,765 or 8.2 cents/mile. My best ever is 22.58 mpg on trip from Dallas to Austin and worst was 9.9 (day at Texas Motor Speedway).
Don't bother asking why I do this cause I don't know either, but it got to be a habit (or addiction) and really doesn't take that much time ... honest!