My dad and I checked the odometer on that old 83 back when interstates frequently had mile posts years before cheap GPS was even a thing.
Back when I was in the hunt for the big MPG #'s, I started off by using a pair of mile markers to get a rough
idea about the odo accuracy. I eventually found out that this was a rookie error, for (I think) in the old Ecomodders
forum their standard of accuracy was to use *10* mile markers at a time. This way, every tenth of a mile deviation = 1% error.
If your odo claimed 10.3 miles had elapsed right when you passed the 10th marker then you knew that your odo was off
by 3%. You could get a pretty accurate feel for the odo error over 10 miles. (Then when we arrived home we
would rub 2 sticks together and get the fire started for dinner. It was a different time in the pre-GPS days. :0)
I always checked the accuracy of the odometers in any car I was tweaking, and was sure to share the 'corrected'
MPG when comparing notes with others. Attached is another pic of a different used Insight that my daughter
Steph & I retrieved from Tucson for her use after graduating college. It would get the rated 70 mpg at 60-65,
but the MPG would droop a little when making time. (Note: The last gas tank bar went out right as we neared
the exit. We cut it close, but I wanted the shot for posterity. :0)
BTW, the refill took 9.7 gallons, (10 gallon tank) ...and yes I had already verified an accurate odo via the 10-mile
marker trick...so it ended up being a 63.5 MPG tank.
Sure, those old 2-seater Insights might have been homely on the outside, but at the same time there some serious
beauty to be had in the vicinity of the instrument cluster.