Amazing MPG gains... Magic fuel, or ???

pnichols wrote:
IMHO, you probably shouldn't rely completely on the consistenty of the amounts of fuel that the gas pumps are putting into the tank at each fuel-up to compute gas mileage.

It is true that there is variation across fuel dispensing nozzles. In addition, automobile manufacturers have designed fuel tanks such that they cannot be filled to maximum capacity. This is primarily because fuel expands as its temperature increases (diesel slightly less than gasoline) and this expansion can cause fuel to leak out of the tank... onto the ground, into the air, or even cause damage to the tank and/or associated emissions equipment.

However, for those of us who own diesel-powered Ram trucks and and who have done the filler vent mod'... when the fuel is at the top of the filler tube then the tank is FULL. This is true regardless of the angle of the surface the truck is parked on.
This is what I see inside my filler tube when I state that my tank is full:


I'll re-iterate what I have stated from the outset in this post; I get noticibly better fuel economy, ceteris paribus, from some tank-fulls of diesel fuel compared to other tank-fulls. This delta is unrelated to altitude or weather conditions, and it is immediately apparent when an empty tank is refilled as indicated by the overhead fuel economy display, there sound of the engine, smoke output (or lack thereof), perceived power output, and ultimately by the hand-calculated MPG value.

-Mark