[Fray Adjacent]

Originally Posted by pcs0snq

To follow up with some additional SG facts..... I told you over the last few weeks that the SG does not log miles travled when the eng is off and your rolling. It does not matter if the key is in position II or I. How this plays with the accuracy of our SG got the best of me and today I did some testing.
As I got rolling on my freeway part of my commute today, I reset the trip odometer on my Fit and reset the SG current trip meter and than watched both. At the end of 10 miles the Fit read 10.0 and the SG 9.9. Pretty decent
So why is my SG miles and mpg always less than the pump Fit trip calc? I know why now. I do some eng off coasting as part of my hypermilling. That's limited to two ways. I kill the eng and roll into a light that changed red when the wait is expected to be more than 15sec. I also on occasion roll off my main street up my neighbor-hood street, up my driveway and into my garage. I do that just because it's an odd chalange, but of course that has some eco rewards. At most, I do that 50% of the available times because of cars in the path. I only do it when no cars or humans are around. It is about 1/4 mile coast max. but involves 2 turns at faster speeds than
normal". I never FAS, as my feeling after doing it a few times is, it was just too much work for the reward. I drive on flat land so have no hills like most of you to coast down.
OK back to the miles issue. As I exited the freeway today, like normal I killed the eng and coasted to this 1st LONG wait light with eng off. From that point, to my office may do it 2 more times. What I recorded when I arived at work was: 18.2miles Fit odometer and 17.2 SG from that point I reset both. So close to a mile of eng off coasting showed up. In addition, looking at the tank miles, I'm at 191 on the Fit odometer and 182 on the SG. That's 5%.
Bottom line the SG is vary accurate with no trim on minel. But, if you coast it throws off the miles and than the MPG for ALL the trip readings. I'll have to look at the written records I have at home and see if this 5% is about what the delta is. I know I calculated that in my spread sheet. This week my SG says I/m 44mpg for the 182 miles and I'm at 2/3 tank of gas left now. So by the numbers I'm really at around 46mpg.
I'm going to contact SG and ask them if they can do something to make it record the coasting miles with ign on... ie switch in pos II
Hope this helps someone

Yep. Summarizes it - turn off the engine, and the ScanGauge is turned off, too. So whatever distance you traveled with the engine off, the SG is unaware of it, throwing off it's economy calculations.