drtravel47 said:
not sure why my calculations at the pump wouldn't be accurate
1)I check it when the pump clicks off; I never go past the click
2) The survey posted noted that overwhelmingly the display was 2mpg higher than trad. calculations.
A question and an observation:
Question: Have you personally measured the gasoline that comes out of the pump? Is what the pump calls a gallon exactly a gallon? Unless you have, you can't be certain that the pump calculation is inherently more accurate than the screen calculation. The fact that many Prius owners report that the screen calculation is a little high may merely be evidence of widespread inaccuracy at gas pumps - an inaccuracy that would increase gas station profits. (Insert ominous music here.:wink
(Digression: Because we've seen these pump numbers for our entire lives, we tend to assume they're accurate. When the Prius gives us contrary numbers, we tend to assume they're inaccurate. This is a natural human psychological trait. In law, it's long been recognized that the prosecution has an enormous advantage, because it presents its case first, and people tend to believe the first version they hear of a story. The defense has the much more difficult task of challenging an accepted viewpoint.)
Observation: The Prius' gas bladder is notoriously finicky. In cold weather it stiffens, which means less gas fits in the tank. As it changes capacity, individual fill numbers can vary widely.
For instance, we had a recent tank that was 50 mpg on the screen, but 53 according to the pump; the next tank was 55 on the screen but 49 according to the pump: I had a bad fill followed by a good fill. This is why, even if the Prius' screen isn't perfect, it may be more accurate for any given fill.