I've got about 1000 miles so far in my FFH, I've just put in my second tank so here is the calculation 547.90 miles, 13.19 gallons which equals 41.5 miles per gallon. This is my primary commuter car, I put in about 54 highway miles each day going to work and back. I try to drive in a manner that follows the FFH dash display for maximum mileage.