MPG guage accuracy

Perhaps at one time the state did the testing. Now, it is the counties that are doing it. I doubt they can just stop certifying the tools of commerce. When I wanted some scales measured for accuracy, they were the ones doing it and the pumps. I see those cert tickets all the time and looks like up to date.

 

It may seem to update slower but that is not the case. It's just that near the end of a tank it takes many more time periods than one six second period to have an effect on the average. This is pure math and has nothing to do with the accuracy of the gas pump or the computer in the Prius.

Mike

 

In Georgia, they put a certification sticker on the pump with the month and year tested. Some pumps will go years without getting recertified.

I remember hearing that they won't retest unless someone actually calls to complain. Anyone know if that's true? (for Georgia..)

 

in theory yes, in reality, no. in our state, pumps are "required" to be inspected and calibrated every 2 years. on average, each pump gets calibrated every 3½ to 4 years.

actually have seen two shows on this and both state that 4 in 5 pumps that showed a significant error, were in favor of the gas station. there is a metering valve that wears out and when it does, it creates a higher reading at the pump.

so this might lead someone to believe that the faster the tank is burned away, the more accurate it could be? so let me tell you my story.

my first two fills were

pump 60.91 MFD 57.8
59.44 and 62

those two tanks were burned up in a few days. (the 2nd tank included a one day 400 mile trip)

then my 3rd tank

53.81 and 63.6!! ya, 10 miles per gallon difference!! that tank took 16 days,

now the one filled today...not quite as bad, but the 2nd largest discrepancy , after the above tank ever in more than 5 years.

62.4 and 68.1.

that tank took 19 days.

hmmm... interesting...half tempted to take off early for the weekend and just drive around to see how close it is if burned off in a few days


as far as the updates changing slower as the tank ages...naw, updates are the same, its simply hard to change the tank average in 6 seconds especially on a tank that has taken two weeks to develop.