It all started when I was driving down a downhill portion of the LIE (Long Island Expressway) following a bus. At the bottom of the hill, I had to brake slightly, but thought I would get 99.9 mpg for that minute segment since I hardly stepped on the gas pedal (briefly at bottom of the hill). I had my 1 Min Cons display on my NAV screen (2012 HB 3). To my surprise, I only got about 25 mpg for that segment. Because of the unexpected results, I decided to turn on the 1 Minute Cons display on the HSI display to compare. I immediately noticed that there was a huge discrepancy between the two in those segments. So, I took pictures and matched them up as per the above. As you can see (RED arrows) there is a big difference in minutes 2 & 3 between the two screens. I would have thought that the info for both screens comes from the same source, therefore would be exactly the same. The other thing that i thought was strange was the regen difference between the two screens. The pattern is exactly the same, but they happen in different minute segments (1-3 vs 2-4). I have some other comparison pictures which I will post a little later. I need time to match them up as per the above.
Thats way more accurat than mine is. My two gauges are seriously in opposition. I was wondering the same thing. Just throwing a guess out, but on the nav screen it shows you 1 minute consumption for the last 30 minutes of driving regardless of if you turned the car off, but the HSI resets each drive. Maybe you had 50 seconds on the ticker when you ended the last trip? idk. Like I said its been intriguing me also.
I agree with it probably being a discrepancy in the timer between the two. Funny thing I noticed - The v wagon doesn't have a consumption graph on the HSI, but I have noticed that occasionally the one on the radio display just reports "dead" minutes. I'll be driving on a flat highway, every bar is just over the 50MPG bar and then there will be one zero spot thrown in as if I was stopped at a light even though I'd been on the highway for 45 min.
I have seen that several times and started a thread on it months ago. Basically no conclusion was reached. I am preparing another one regarding this topic and will post as soon as I complete the comparison.
Here is the second one I have been working on. As you can see, minute 5 (RED) in the NAV, the mpg is 0, whereas in the HSI the mpg is about 35. In minutes 6-12 (GREEN) on the NAV every segment is at the max. But on the HSI it varies in minutes 6-10. All of the regens are off by one minute between the two displays.
My guess would be that the mins at the two displays might not have started and ended at the same time. For example, one could be from time 0-60, the other could be 11-71, and thus included different range of data.
It doesn't make sense for my post above where it was showing 100 mpg for 7 minutes in a row whereas the other only showed it for 2 minutes.