On Thu, 20 Jul 2017 12:08:33 -0000 (UTC), Mad Roger
wrote:

What is a realistic accuracy & precision of typical MPG measurements when
measured by the consumer using the typical method of dividing their
tripmeter miles by the gas-pump gallons during fillup?


This thread reminded me to run-the-numbers from my car's log book.
I record each fill-up and a few times a year I'll plug the numbers
into a home-made spreadsheet.
I'm not sure if my car even has a built-in calculator - I'll have to
check .. my brother's Buick will always show about 1 mpg
better than reality.

in liters per 100 km my last 10 fill-ups are :
6.5 8.0 7.3 7.9 7.0 7.4 7.4 7.4 7.3 7.4 avg = 7.36

The adjacent high/low values indicate that the fill-up was
filled-to-the-brim or not-quite-full due to the pump sensivity.

Interesting to compare winter driving with winter tires :
8.3 8.7 8.2 7.9 7.7 8.0 8.5 8.3 8.0 8.0 avg = 8.16

2015 Kia Rondo 6 speed auto ; 2 liter gas ;
rated 10.6 / 7.6 city/highway at Natural Resources Canada
http://oee.nrcan.gc.ca/fcr-rcf/public/index-e.cfm

John T.