Using Interstate Mile Markers to Calibrate an Odometer

[Mr. Kite]

I recently drove about 1,000 miles in my HiHy (from CO to AR) and used the handheld GPS to calibrate my odometer along the way. I would record the numbers from the trip odometers from the handheld GPS and the HiHy. These were all nonstop datasets consisting of just under 100 miles each (after 100 miles, I lost the digit after the decimal on the handheld). For each of these sets, I plotted GPS odo vs. HiHy odo. I did not include 0,0 as a data point since there is some error in my manually resetting the two devices. I then obtained the slope from a straight line fit to get the error. Through 5 little sets of data, the slopes were 1.0344, 1.0351, 1.0337, 1.0329, and 1.0351. This averages to 1.0342 (the HiHy's odometer needs to be increased by 3.42% to be accurate). I will collect more data on my return trip before I update my tank entries.