Does anyone know why a 4x4 06 pathfinder gets better mileage. We always measure my wifes pathfinder gas mileage and she gets between 18.5-20 city and 21.5-24.5 hwy. We have tested it tons of times. My x never sees over 20 no matter what and we both drive pretty normal. I think it might be because of the premium fuel we use in the pathfinder. Also the patfinder got 26.8 mpg on a 250 mile trip that we averaged 60 mph on. We test by: miles driven since last fill up divided by gallons of gas to fill up. Is there a difference in the transmissions on these trucks? What would cause this? Aerodynamics?