reset average display

The sceen average is what you're talking about?

It only shows the average since it's last reset, and it resets automatically when you fill up.

Apparently that was different on the Classics.

So, there's no 'lifetime average' kept on the screen. You have to keep it by hand. There are some good spreadsheet templates floating around.

So yeah, if you reset Trip A when you fill up, your screen will match Trip A.

 

I may be wrong, but fairly certain the screen display showing average fuel consumption is reset each time the fuel filler flap is opened.

 

I'm not sure about that. People have reported that it resets only on a fillup. Some folks say they have added a couple of gallons at times without a reset.

Haven't tried it myself though, so not speaking from experience.

 

No, it doesn't reset when the fuel door is open. At least on mine.

 

It's not the fuel cap.

If your tank goes below a certain level (not sure what level, because I don't care all that much ), and then goes all the way to full, the MPG counter resets automatically.

Next time you fill up, start the car and wait. You'll see the fuel gauge go from empty to full slowly, in about a minute. When it gets to full, the MPG counter will reset.

I assume what the OP was saying was that after a fillup, he reset his trip odometer but not his MPG counter. However, the MPG counter reset itself anyway, making it look like the MPG counter was "tied" to the trip odo that had just been reset.. but it's not.