Morning, xcel. Great post – I’m, unfortunately, playing with an analytical handicap. And although I’m going into the deep, dark forest with a pen light, here goes:

Some of my thoughts/arguments are based on the Garmin I previously used. Unfortunately, the Honda GPS gives much less information, such as how many satellites it’s locked into. It’s amazing how quickly I forget things, but I *think* the Garmin usually had at least 9 satellite locks at any given time. What the Honda manual does say is that it has 24 satellites available, and although I know they can’t pick up all 24 at a time, I think 9 would certainly be probable – likely the same 9 that Garmin picked up.

Regarding the missed placement on the Navi map, this is more a function of a mis-mapped road, which I also have in my residential area, and a couple other places. For the most part, it’s accurate, but every once in a while…. Speaking to the Garmin again, the mileage calculation is not affected by the “jump”. The internal calculation has you at the same place it did before the jump – it’s just adjusted your placement on the visual map to something that is more likely correct. Once again, it’s figuring distance traveled, but the picture of the road may be slightly off – particularly on non-major roads.

Now my disclaimer: I *know* that the GPS is not 100% accurate. However… I also *know* that the odo is also not 100% accurate (even the speedometers are inaccurate - but calibrated to be most accurate at highway speed). And… I *know* that there are published reports of gas tank registers not being 100% accurate. And… there seems to be evidence that gas shrinks and expands in volume in connection to temperature, which can also affect accurate calculations.

Basically, it comes down to this: we can’t know *exactly* what we’re getting. Regardless of what you choose, you will be close – even, I would say, within a statistically acceptable claim. But what mechanisms do you trust? Considering the above paragraph’s arguments, *I* just trust the Navi.

As far as what is the legal standard, you have me on the odo. However, this post might get a bit more heated were I to discuss other “legal standards” that are suspect….

Disclaimer #2: Navi is a *bit* more optimistic and that could have some influence on my opinion. I would like to think I would argue the point if I was simply a walking pedestrian, but there’s no way to know.

At any rate, you make a good argument and I’ve enjoyed the debate. Thanks.

'05 Accord Hybrid
'05 Odyssey EX-L
'03 1800 Goldwing
'98 Civic EX (16 yr. old daughter's)