: Low gas indicator and MPG calculation



marathonman89
10-22-12, 01:01 PM
Hello all,

Below comments refer to a XTS Premium Trim with instrument panel set to balanced mode.

Got a low fuel indicator warning on the instrument panel and the option to dismiss. I did so and then noticed that the fuel tank icon in the lower right of the instrument panel turned to yellow. Perhaps if you are going on "fumes" it turns red. Looked at the owner's manual when I got home and it appears the color change is an undocumented feature.

Topped off, the trip odometer showed mpg to be 17.4. However, I did the math on a calculator and the actual mpg was 21.9 (80%city and 20%highway). Looks like in my case the mpg calculation is off by about 4.5 mpg.

flying fossil
10-22-12, 07:14 PM
I think your stuck with the low level indicator. I know of no other way to check it. As to the MPG, I never use the cars computer. They are all over the map.
I keep track of the gas and maintenance on my cars and always do actual usage calculations.
Now, is the odometer correct ?????

kipsts
10-23-12, 05:25 PM
I think your stuck with the low level indicator. I know of no other way to check it. As to the MPG, I never use the cars computer. They are all over the map.
I keep track of the gas and maintenance on my cars and always do actual usage calculations.
Now, is the odometer correct ????? Somewhat related to your question flying fossil, yesterday I had my Escort radar running and found the GPS speed to match my XTS speedometer. Of my cars that is only true for the XTS and the C70, my Porsche is off by about 2 to 3 mph at the higher end.:cool2:

blue_skies
10-27-12, 02:47 PM
Somewhat related to your question flying fossil, yesterday I had my Escort radar running and found the GPS speed to match my XTS speedometer. Of my cars that is only true for the XTS and the C70, my Porsche is off by about 2 to 3 mph at the higher end.:cool2:

My Porsche is the same - and I was told that this was to guarantee that the actual speed will never exceed the shown speed, within all tolerances, such as tire setup and wear. Same is true for my motorcycle.

There is a CHP setup in our street that I pass daily, showing the measured speed. Both the old STS and new ATS are dead on, whereas the Porsche has this progressive offset.

Get an mobile app that shows your speed, or use any GPS system to do the same. These will show you your actual accurate (GPS-based) speeds as well as actual (logged) travel distance. I tested a few, and on the newer cell phones and GPS systems, I found these measurements to be quite accurate.

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Hello all,

Below comments refer to a XTS Premium Trim with instrument panel set to balanced mode.

Got a low fuel indicator warning on the instrument panel and the option to dismiss. I did so and then noticed that the fuel tank icon in the lower right of the instrument panel turned to yellow. Perhaps if you are going on "fumes" it turns red. Looked at the owner's manual when I got home and it appears the color change is an undocumented feature.

Topped off, the trip odometer showed mpg to be 17.4. However, I did the math on a calculator and the actual mpg was 21.9 (80%city and 20%highway). Looks like in my case the mpg calculation is off by about 4.5 mpg.

Did you reset the mpg both times when you filled up? If not, it is aggregrating from the prior usage.

On my old STS, I found that the mpg measure did not really care about the reset point - it was just a restart - it would average over the last 100 miles driven or so, and would never match a 300mile trip. But try a quarter tank and it seems pretty accurate.

The remaining miles prediction is actually more accurate if based on your last 100 miles than if based on your last 300 miles, e.g. when you go city->freeway or freeway->city, the prediction should change more rapidly than slowly.

CDN XTS
12-10-12, 02:52 PM
Found out calculation by STS was not accurate - ever. But Manual calculation is tricky, unless you are very acurate when filling up the car. Seems the usual "shut-off" is not always at the same point.