On Thursday, July 20, 2017 at 4:31:25 PM UTC-4, dpb wrote:
On 07/20/2017 2:06 PM, trader_4 wrote:
...

I think that's hogwash, too. The mpg is volume/distance; the
computation is independent of the energy content; simply a higher
consumption rate/lower mpg value will be computed.


Why is it hogwash? They seem to be saying the same thing you are,
that the energy content means that what you see as MPG will
vary because of it. If you have gas with higher energy content,
then you'll see 25 mpg. If it's lower energy content, you'll
see 23 MPG. How much the energy content varies, when it's
labeled as the same product, eg reg unleaded, IDK. It would
obviously vary depending on the amount of ethanol added.

Maybe he meant that; wasn't exactly what I thought was trying to say...

I thought he was saying the algorithm was _imputing_ miles travel based
on an assumed reference energy content; if he was instead just trying to
explain that the energy content of the fuel on a volumetric basis has an
effect on the total energy in a gallon of that same and hence how much
one gets out of a gallon, then we are in agreement.

And, of course, the mpg is the inverse of the ratio as I wrote it
earlier... (I was going to talk about distance per unit input but
decided it would get too longwinded and didn't fix all the initial to
match the final.)

--

Until proven otherwise, I'd say what he's saying there is what you
say and what I would expect, that it just uses volume of fuel
injected and miles traveled.