Re: Accuracy of MPG Readings
 

Everyone, take a deep breath, relax.

....And it's tank average over the last data points since the reset...:P

Re: Accuracy of MPG Readings
 

I thought that was one of my thoughts - :P back at YA ;)

All is Cool!!

Re: Accuracy of MPG Readings
 

We'll after continuing to watch the white avg line for a few more tanks, I guess I have to back away from the 15min average statement, and lean towards what others are saying about the tank average.

What has confused me is how quickly this number can change with very little mileage change.

I've been used to my Garmin GPS unit for the past 3 years. It gives you an average driving speed. At first this average changes rapidly based upon your speed. But once you get over 400 miles (or one of my 3,000mile one way cross country trips), To go from a 56.5 mph avg to a 59mph avg while driving on the freeway the whole time at 60-70mph takes all day if it budges at all.

Now this tells me that the MPG figures must be very Volatile unlike avg mph figures, and just a slight change in driving characteristics can change your average drasticly.

Of course if the NAV would retain more data it should become less volatile.

What's the longest someone has gone without resetting the NAV white line average? Did it become less volatile over time? Or do the majority reset it per tank?

Gary

Re: Accuracy of MPG Readings
 

It does not appear there is anyway to connect to the Navi to determine the data average information. The best way I can think of is going thru the manufacture for an answer. It all seems to point to a hour clock IMO. For instance, yesterday the winds here were favorable for some good MPG. I presently have 20.7 hours on my tank according to the SG, but I was able to pull 1.7 MPG Navi average over the SG tank average yesterday. Both gauges were reset at fill-up. According to the amount of fuel used from the SG tank reset, the Navi was off by 1.5 mpg average because it had dropped data on the present tank. The SG showed about 6 miles less than my trip OD which I went by. That accounts for the .2. mpg average less than the SG.

Gary, I would be completely in the dark about the accuracy of the navi without the SG to compare it with. There within a few tenths average after reset untill the SG hits between 10 and 20 hours driving. I and other's here, estimate half the data is being dropped once the navi memory is full. In the example of my driving yesterday, I had great MPG and the navi increased faster compared to the SG. The oposite will happen if I get poor MPG, the navi will drop faster and go below the SG reading. The fact is, unless you have some drastic changes in MPG near the time you fill up, both gauges should read within a few tenths. This is why my conclusion is the navi and the message center averages are better than what you get at counting the gallons at fill-up.

In my opinion, take the average on the navi or message center and record them as your true reading unless you have drastic changes high or low just before fill-up. If you want to know your true MPG at all times, get a SG or something that can carry all the memory of the entire tank.

GaryG