I know I'm gonna get flamed for this, but,
On 1996 and later Rangers, or any vehicle that uses OBD2 the only way to get true mpg is with a Scan Gauge or something similar. The method of using gallons divided into mileage, unless you are using the exact method everytime doesn't work that well. It will give you a general figure, but not accurate to measure one mpg more or less. Variables like the truck leaning to one side or another, even by 2 or 3 degrees, the slant of the surface the truck is sitting on, the amount of weight in the bed, unless exactly the same from fill up to fill up, will have an effect on the amount of fuel that your tank takes, thus giving an inaccurate reading. Even the time of day and the temperture can have a slight effect on the amount of fuel that the tank takes.
Just putting in or leaving out 1/4 gallon of gas can easily make up or delete that 1 or 2 mpg from one fill up to the next.
Just saying that a difference of 1-2 mpg shouldn't be any cause for worry, and yes, the winter fuel does make a difference but you have to take into consideration all the variables also.
Scan Gauge works directly off the ECU and is going to give you much more solid and accurate info. I run one on our motor home and wife
s Subi. Will probably get one for the Ranger this season...invaluable for monitoring the trucks systems.
OK, start flamin me...
Grumpaw