It is always off by 2 to 2.5 mpg every fill-up. Same pump, same procedure when filling. Pump to full to auto shut off, 10 sec then pump to auto shut off, 10 sec then auto shut off then done .
Normal. We even have old threads comparing our individual inaccuracies, which vary by car / driver / conditions. Unlike speedometers and odometers, there are no legal or industry standards for this 'lie-o-meter'.
Sounds about right (my average over two years has been +3 mpg, or about 6% optimistic on the dashboard). I mentally subtract 3 mpg from the consumption number on the HSI. My detail: Tableau Public
Here's a monkey wrench you can try to catch, techstream has my speed 1 to 3 mph slower than dashboard display constantly, running on 15" tires.
Mines usually 2-3mpg higher then actual. I also have 2~ gallons of gas left when the beeper goes off. My speedometer is 1-2mph higher then gps. (gps has been checked over time with different vehicles)
