Has anyone experienced a situation where everything on the trip computer works except for the average MPG, which is stuck on one reading (i.e., says, for example, 21.9 no matter how you drive from them on)?

When was the last time you reset the trip computer?

If it has never been done the avg mpg will probably not change no matter how you drive for short spirts.

To rest move the control the avg mpg and hold the reset for 1 sec. You can do the same to reset avg mph and miles. You can reset all 3 by going to miles and holding the reset for about 3 sec(the "select bar" next to each will come on).

Yes, I should have mentioned that. If I reset the Av Mpg it kicks back in for a while. Seems to be something about when it gets low on gas. At least I've never seen it happen with a full tank.

I have the same car 99-S70 GLT as you but I don't think I have a trip computer.

Is this an option?

I believe you do have the readout but not the switch. Does

your car display temperature (I think S70s GLTs do even without

the trip computer though older ones do not)? To add the trip

computer you would need the switch from a dealer and they would

have to enable the software (an extra charge in addition to

the switch). The trip computer would give you

average speed, average MPG, instant MPG, distance travelled since

reset, distance to empty, and temperature (you can only display

one of them at a time).

Dennis,

The trip computer is an option on the GLT, so you may not have one.

If you do the display is under the speedo next to the clock. The control will be located on the dash next to the mirror/rear window defroster. It will be a knob with the word "INFO" above it and a reset button in the lower right corner.