LMPG meter drives me nuts

griller · 06-01-2008, 03:03 PM

Does anybody else have their LMPG meter skip tenths?

I recently changed my route to work, and have experience a dramatic increase in one way mileage. The morning commute gets me up close to 70 mpg pretty regularly. (The afternoon is about the same mpg as before, about 60-61). So I have been watching my LMPG climb.

The LMPG meter does not climb smoothly, it can bounce up and down over the course of a week or so, but surprisingly it bounces by more than one tenth. Sometimes the change can be as much as .3 mpg.

I've noticed that the increases can be .2 or .3 mpg even if it doesn't flip back and forth between higher and lower mpg.

Is this some kind of weird statistical sampling issue? Does the Insight calculate the LMPG at odd moments?

I put together an excel spreadsheet that calculates how many miles I have to travel at a given mileage, to get to the next bump up in LMPG. For me that is at 59.5 mpg, I should be getting very close, if not past that mile on my odometer (I have to guesstimate what mile I hit 59.4 at). But if I have to wait till 59.7 it could take as much as 35000 miles before I see the flip-over, we're talking 6 months of driving to see that increase..

Cheers
griller

**uhtrinity** · 06-01-2008, 03:12 PM

Like Iamian pointed out the system calculates in metric, then does a conversion to english. That is why you see those 0.2 and 0.3 jumps and drops.

You could always reset you lmpg, I did when I first bought the car and have considered doing it again since I went phev.

griller · 06-01-2008, 05:23 PM

ah,
Thanks for the reply, it's a rounding artifact I guess.

I don't reset the LMPG because I want to be able to easily calculate how many gallons the car has used.
I'm the original owner, so aside from the dealerships barbaric practice of running the car to charge the batteries, I have only myself to blame for the LMPG reading as it stands today.

james · 06-02-2008, 01:03 AM

Why not simply avoid the problem? Keep the display on one of the trip gauges, and reset it at every fillup.

I doubt whether I look at the LMPG more than once a month or so. The per-tank display is far more useful, as it affected by current conditions. If I saw a significant drop (without an obvious explanation like snow or trips to the mountains), I'd start looking for the cause.

griller · 06-02-2008, 09:31 PM

Ok so I'm obsessive lol

I keep trip B on the tank, I set trip A every morning before going to work, and reset trip A before starting home in the evening.
I check all three when I arrive at work or home.

On the weekends, I set trip A for the whole weekend. Sheesh, weekend mileage is miserable. It drove me to buying a bicycle trailer to go grocery shopping. Still some trips are unavoidable.

Cheers
griller

nstn8 · 06-03-2008, 11:21 AM

My jumps by .2 or .3 as you have stated as well... I kinda like it though. Just bought my insight about a month ago probably with a LMPG of 53.3 with 120k miles on it. This car was driven hard or fast or both. Since purchasing I reset trip B as my personal LMPG which is approximately 66mpg currently. I use trip A for each tank of gas(just filled up this morning 695.6 miles 70.5mpg), and use the segment display for each trip I drive to and from work. My LMPG has risen to 53.8 mpg and I couldn't be more ecstatic. This car is absolutely amazing.

red1dr · 06-03-2008, 01:18 PM

Quote:

Originally Posted by griller

I'm the original owner, so aside from the dealerships barbaric practice of running the car to charge the batteries, I have only myself to blame for the LMPG reading as it stands today.

You make me laugh - now. When I picked my Insight up from the dealership, the LMPG read 6.7 because they idled it to charge up the new batteries. Only I misread it as 67 and thought it was doing pretty well. I was outraged when I figured out what had happened, but they were only following the instructions in the manual.

james · 06-03-2008, 02:40 PM

Quote:

Since purchasing I reset trip B as my personal LMPG...

You do know that the A & B trip meters will roll over after something like 2K miles?

griller · 06-03-2008, 11:00 PM

OK, so I went and changed the readout to liters per 100 km.

the reading was/is (and I checked it twice) 3.9l/100km. (over 29,497 km)

By my calculation that means my lmpg should read 60.3 (rounded from 60.26903).
BUT MY LMPG METER READS 59.4!

either my math is wrong, which the actual calculation is being done by Excel, or the meter in mpg is waaaaay late in reseting.

grrrrrrrriler

red1dr · 06-04-2008, 05:33 AM

Could it be due to rounding? Suppose it was actually 3.94 l/100km, which would display as 3.9. Doing a rough conversion (please check my quick math), this would give 59.7mpg.

I run a spreadsheet in which I record (obviously) odometer reading, gas bought, calculated mpg for the tank, and calc LMPG. But also the tank mpg and mileage readings from tripmeter A and the LMPG readings from the display.

Calc LMPG has always been a tad LOWER than the display LMPG (79.73 vs 80.6 at the moment) but I figured this might be due to discrepancy between how the Insight measures volume of fuel and how the gas pumps measure it. I take the lower pump numbers as the "accurate" ones. Of course this discrepancy does not enter into the numbers you are looking at.