Perhaps some longer-term owners can chime in with some words of wisdom. I do sometimes see my GOM go up by a mile or two if I go down a lengthy downgrade with the regen showing it's charging. The GOM on my old CR-Z hybrid would make fairly radical readjustments after a few miles if the type of driving I was doing changed radically. Suddenly it would show 30 miles or more of increased or decreased range.
Based on my experience (about 30k miles with the Kona), it appears that the Kona keeps track of your driving habits. I'm not sure how many miles are used to calculate the average but I would estimate that it takes the average of 400 to 500 miles.. One thing that it seems to do for sure is that it always re-calculates the average as you keep driving.. Let's say hat the car averages 500 miles for the GOM. If the first 100 miles in your 500 mile average were let's say 3.5 mi/kwh and you drive 100 miles at 5.5 mi/kwh, your range will suddenly jump up a lot. However, if the first 100 miles in the 500 mile average were a 5.5 mile average, you will see no difference in range even if your average at that point was 4.5 mi/kwh. I'm not sure if I'm expressing my observations in an understandable way.. The reason why I believe that it works this way is because sometimes, my GOM shows like 240 miles at 80% and then I drive 100 miles at 5.6 mi/kwh (which translates to more than 240 miles range at 80%), sometimes my GOM went actually down.. Sometimes, the opposite happens.. Sometimes I have about 250 miles range at 80% and then I drive 100 miles at 4.1 mi/kwh and surprisingly, my 80% went up.. The only way to explain is that the distance of 4.1 mi/kwh is replacing was lower than 4.1 mi/kwh and therefore the range went up.
Let me give you one example: 500 mile averaging period.
100 miles on 6/1 at 3.9 mi/kwh 25.64 kwh used
100 miles on 6/2 at 5.6 mi/kwh 17.85 kwh used
100 miles on 6/3 at 5.0 mi/kwh 20 kwh used
100 miles on 6/4 at 4.0 mi/kwh 25 kwh used
100 miles on 6/5 at 5.5 mi/kwh 18.18 kwh used
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500 miles driven, 106.67 kwh used, average of 4.687 mi/kwh * 64 kwh = 299.96 range at 100%
Now if I drive on 6/6 for 100 miles at 5.6 mi/kwh, I'm replacing the 100 miles on 6/1 at 3.9 mi/kwh, so we subtract 25.64 from the average and add 17.85. So, now the average for the last 500 miles becomes calculated with the new total of 98.88 kwh for 500 miles which now translates to an average of 5.056 mi/kwh.. Multiply by battery size of 64, the 100% range will now be 323.
Now, if you drive 100 miles on 6/6 at 3.9 mi/kwh instead of 5.6 mi/kwh, your 500 mile average will be unchanged as you are replacing a period of 100 miles @ 3.9 mi/kwh with another period of 100 miles @ 3.9 mi/kwh.. So, even though you drove 100 miles at an average below the 4.687 mi/kwh you originally had, your range won't drop as the 100 miles that your are replacing were also at 3.9 mi/kwh.. I hope that this makes sense.. As I said, this is the only conclusion that I came to to explain why sometimes, I drive quite a distance below my GOM average and yet, my range stayed the same or even went up. The only way that this could happen that it is a rolling average where the latest distance travelled replaces the oldest one in whatever distance it averages.