In Reply to: Clarification... posted by Tim Collins on November 04, 1999 at 00:41:58:
If you shift the automatic transmission to a lower gear while going down hill (engine braking) you can peg the needle all the way to the left (max mpg.)
I think Joe above has go it right about the fuel being shut off during engine braking and after a certain rpm. If the processer does not sense maximum vacuum condition the fuel will not shut off(hence the automatic cars will not behave like the stick shift cars).
I am pretty sure a processor uses a vacuum signal along with the odometer signal to get the gage to reasonably estimate real time mpg.
Interesting observation though isn't it? Jim