[special-K]

This question is impossible to answer accurately. Two identical trucks can get different mileage...as if there was an identical truck. You need to figure out how far off your speedometer is off.Is there anywhere with mile markers? Or,have someone follow you at a specific speed and compare readings. At the moment I have no gas gauge and no speedo. I had twp similar trucks. One day,I filled the one with speedo and gas gauge up,wrotethe mileage down,went to the job,and back to the same gas station and filled up again,and figured how many miles I drove and exactly how much gas it took. The next day I did the exact same thing with the other truck. Since I knew how far it was from the gas station and back and how much gas it took I could figure my mileage.