I checked my odo compared to GPS and I am at a 5% difference. Odo reads 9.5 miles and GPS says 10 miles. So 17.79 plus 5% = 18.72mpg...not great but better than 17.79. I have 265/70/17 revo's...Those are highway miles and I drive like a grandma! I also have the V6
FALLS..your math is off...