why do the mileage ratings vary so much between v6 engines?

i recently found out that a person that i know has a relative who works for ford and i asked a similar question, since i am looking into purchasing a 2012 model.......the 6 cylinder engine is going to get 18 mpg on the highway....the 4 cylinder engine is listed at 28 mpgs for the highway, but really gets 26 mpgs on the highway with 20 in the city......the 4 cylinder motor is the better option, if you do not have to climb steep hills.......it gets almost the mileage that it is listed at; 2 miles less per gallon......i presume that since the 2011 with a 4 cylinder motor is listed at 27 mpgs, it will get 25 mpgs on the highway......i wouldn't expect the v6 motor on a 2011 to get near what is stated, if the 2012 doesn't ..........just be careful......also, when you test drive it, you can clock the mileage on that vehicle.......there is a switch next to the lower left side of the steering wheel to check the mileage.....it'll be not far from where your knee rests......ask the salesman about it and how it works....... also, my father is very good with cars and he recently test drove the 2012 model with a 4 cylinder and 6 cylinder motor, he knows what to look for and so forth from past experience with building race cars.....he felt that the 4 cylinder motor had great pull and pretty good timing.......i think that you will be ok with the smaller motor, if gas is your concern.......... also, the vehicle takes universal fluids.......you will not need to use any special kind of fluid that is expensive...... i hope that this was some help.......

you can ask about fluids at your nearest auto store as well, but from what my father states, nothing out of the ordinary and expensive will need to be used.........also, our mechanic said that this is an all around good suv with a pretty good rep....... just some opinions.....take them as you like good luck with everything!