Jim, the overdrive on the A4LD and AOD are an integral part of the trans,
and therefore shifting in or out of overdrive was no different than any
other gear; automatics were designed to shift up and down. The real problem
was that the calibration of the engine controls had not yet reached the
level to allow high load combined with low rpm, which resulted in many
driveability concerns, including shift hunting. Fortunately, that is in the
distant past now. The fact is, that in city driving, the overdrive does
nothing for fuel economy, and that was the question that I hoped I answered
for the poster. As for whether or not you could acutally harm the
transmission, that debate could rage on forever, but I have never seen any
hard evidence of it, so let's not muddy the waters here, ok?
"Jim Warman" <email@example.com> wrote in message
> Errmmm, some transmissions (the A4LD comes to mind) will "hunt" under
> certain urban driving conditions.... newer transmissions "generally" avoid
> this through electronic strategy.... older transmissions depending on
> mechanical indications are hardest hit.
> Both the A4LD and the AOT could fall prey to the extra stresses, heat and
> wear associated with the condition. When offering advice, we should always
> strive to err on the side of safety.
> "Ted" <firstname.lastname@example.org> wrote in message
>> No, very little difference at all; overdrive will increase gas mileage,
>> but the effects will be the greatest at highway speeds. Think lower
>> engine rpm=best economy. By the way, there is nothing to gain by
>> cancelling overdrive operation in town, this is why it is enabled by
>> default with every key cycle.
>> "Paul O." <email@example.com> wrote in message
>>> Just curious, I have never used overdrive in town, but have been
>>> wondering if it makes any difference in gas mileage to speak of? Thanks.
>>> Paul O.