[wolfox]

Simple really. Fill the tank. Zero the trip odometer. When tank drops to 1/4, fill up again, record the trip odometer readout before zeroing the odometer again. Record how many gallons to top off tank. (When the pump shuts off with a click in the handle)

Repeated over a one month period every time I fill up when I get to 1/4 tank. Always recording trip odometer and gallons to fill up on the pumps. Then, I just sum up all miles, all gallons, average them,( anything below a .5 gets rounded down, anything over .6 gets rounded up) then apply the final formula of miles/gallons.

I will have more definitive numbers after I return from my 800 mile roadtrip and see how much she eats. I am expecting a serious drop because I will be moving 700 pounds of passenger (two of my friends are REALLY big - the other guy could sit in the center console drink holder) and I guesstimate to be an additional 160 pounds of luggage at least. There is going to be a slow, sloping incline to climb to get out of the Ozark/river valley here so I think I will get more realistic numbers there over a broader range of terrain. Mostly, I have been sticking to town where there is mostly 45~50 MPH back-roads, flat as a board. Getting her up to speed on a 70 MPH highway may totally kill previous calculations, but would be IMO, more realistic.