On Sun, 23 Jul 2017 02:31:23 -0000 (UTC), Mad Roger
wrote:

On Sat, 22 Jul 2017 21:03:45 -0400,
wrote:

and exactly how is that germaine to the issue at hand? The speedo
means NOTHING. All we care about is the ODO - which will ALWAYS be
consistent, even in inaccuracy - so can be easily compensayed

While the odometer has a decimal place, the tripmeter generally does not.
Backwards, my boy. Every car I have ever owned with a trip odo has
tenths on the trip - many (or at least a few) with trips do not have
tenths on the main ODO

So anyone using the tripmeter/pumpmeter calculation has no scientific right
to include the decimal place in the mpg calculation.

Get a LIFE!!

It's (mathematically) impossible to calculate 19.5 mpg when the tripmeter
reading doesn't have a decimal place.

But it DOES - and you don't have to use the trip odo if you don't want
to. Use a pen and paper (you remeber those?) and write down the start
mileage when you do the first fill up. Keep track of all fuel added
AFTER that mileage, and at the last fillup, total all the fuel added,
write down the current mileage, and subtract (as an engineer you DO
know how to subtract, right??( - the difference is the total mileage
covered. Devide that number, complete with tenths,by your total fuel
consumed, to the tenth of a unit, and you have your accurate fuel
consumption, to the tenth of a MPG ( or in the case of a car
calibrated in Km, to the tenth of a Km/liter - which is a WHOLE LOT
more accurate.

Likewise, it's (mathematically) impossible to calculate 19.5 mpg when the
fill-level estimation isn't accurately known to some vague concept of less
than a gallon.

But if you are as smart as the average fifrg grader you KNOW it is
possible to get a LOT closer than that. Fill till the fuel is visible
in the filler neck, at the lead free gas restrictor plate, and you are
accurate to within about half a cup full in the vast majority of
cases.

The only reading, if the three required, that is reasonably accurate
(someone quoted some figures already for the pumps, which I appreciate), is
the pumpmeter itself.

But that pumpmeter reading is completely dependent on the fill-level
estimation, which isn't known to any reasonable degree of accuracy.

Bull crap

I agree the way to get around the horrible fill-level inaccuracy is to
average over numerous tankfulls, which helps greatly, but doesn't eliminate
the two major inaccuraciesa which make it impossible for a mom-and-pop
tripmeter/pumpmeter calculation to have a decimal place in the result.
Bull Crap.