It's a mystery to me, Jean.  After working well all summer, my tank has been
acting strange since the cold weather set in.  Makes me think the bladder
isn't pliable enough to fully expand.  When I gas up, usually with one bar
remaining, sometimes blinking, I'll take anywhere from 7 to 9 gallons or so.
I don't press the reset button (it's supposed to do this automatically after
a few minutes and always does) but I'm no longer confident in the "full"
reading.  All summer I used the "rule of 10's" (multiplying my mpg reading
times 10 to estimate my range) but since the cold weather set in I get a
blinking bar 100 miles before the product of that calculation.

How much gas did you put in?  If you filled the tank, it certainly should
have registered.  If you put in just a few gallons, read your manual, it
says that it won't register if just a few gallons are added.  Note that the
reset button has nothing to do with the reading shown on gas gauge.

In cold weather pump gas as fast as you can. No matter what the amount is
when it clicks off leave it at that.  Wait at least a minute before putting
cap back on. I leave the cap off while I'm inside getting receipt.  Tank
reads full immediately.
Something tells me you may be leaving the car "on" while you are pumping.
Yes, no?
I just came back from a 407 mile round trip to NH and back to MA. 70 miles
an hour until reaching MA border (I-91) and there was snow and a huge backup
right to exit 46 northern CT.  I took the backroads to get home. 9.05
gallons at the same pump as when I left. I had the blinking bar and audio
"ding" and message on the screen. Heck, it's better than only having a few
ounces left.

mark_