My average MPG over the last 70,000+ miles is just over 30 MPG (total miles divided by total gallons used). The PCM dash MPG always reads LESS than actual (typically around 1 MPG).
I've got an Excell Spreadsheet that I put my miles, gallons, as well as cost per gallon in every week to keep track. Also keep track of "PCM MPG" reading & "Miles to E" at each fill-up and RE-SET the PCM MPG at the beginning of each week as I get on the interstate Monday morning.
Have hit 32.xx MPG about a dozen times, but have yet to break 33 MPG.
Manual & 2.73 Gears
stock 235/50-18 tires @ 36 PSI
91 Octane Ethanol-FREE fuel (since new)
SCT Bama 91 Performance Tune
AirRaid Cold Air
Dynotech Aluminum Driveshaft
Drive from N-E Wisconsin to Chicago every week (400 miles total)
75% interstate driving @ 75 MPH and cruise on
10-15% 30~45 MPH stop/go
10-15% 60~85 MPH interstate w/o cruise
My Stangs ...
1969 Calypso Coral 351W 4V 4-Spd 3.50 T-Lok Deluxe GT Hardtop (owned since '81)
2016 Guard 2.3L Ecoboost 6-Spd MT Base Fastback, 641, 66W, 13D, 47AX O-T-T Stripes (ord 2/11 ~ del 5/23 ~ mine 5/26)
2011 Kona Blue 3.7L V6 6-Spd MT Prem Coupe, 203A MCA & HID's (0-129k mi)
2004 Comp Orange, 1998 Chrome Yellow & 1994 Bright Blue V6 5-Spd Coupes (0-126k, 131k & 89k mi)
1979 Fairmont Futura w/ '85 HO 5.0L, built AOD, 3.27 T-Lok + more (a Stang w/real back seat & trunk)