My car has a button on the transmission lever to select between
"sport" and "economy" settings. (Yeah, it's an automatic; not my
first choice, but beggars can't be choosers and driving an automatic
isn't really bad enough to complain about.) When I took possession
of the vehicle it was set to "economy", and since the performance
failed-to-suck I just left it there. But on the most recent tank
of gas I figured I'd experiment, and drove the entire tank with
the button on the "sport" setting. I wondered just how much
difference to fuel economy the button made.
The car does feel different when I change the setting,
and yes, it does feel more "sporty" or "sportscar like" in a mostly
subjective, partly describable way. In some ways choosing "sport"
made it feel a little more like a manual-transmission car despite
my not having to shift. I expected the big change to be the shift
points, that it would shift a little later in "sport", but I noticed
a difference when not accelerating as well. Taking my foot off the
gas resulted in more engine drag and a more noticeable drop in speed
than when the button is set to "economy" ... making me think, "clutch
instead of torque converter?"
My gas mileage for this tank was slightly better than
average. Not so much that it couldn't be random variation (and
there was that one weekend when I didn't drive as fast as usual,
but the rest of the time I've been driving normally), but it's
a smidgen better than the highest fuel economy I'd gotten in this
car to date. I found this a little surprising.
Of course, this also has me thinking, "using the
clutch more and the torque converter less?" -- that would
explain both the sensations and the slight increase in fuel
economy. But it wouldn't explain why the clutch (assuming my
car actually has one, which I suspect but have not
confirmed) isn't used more often in "economy" mode. After
all, wasn't the whole reason for adding clutches to four-speed
electronically-controlled automatic transmissions to improve
gas mileage?
(What I don't know is whether all four-speed
automatics have clutches or not. The first four-speed I
drove, a Pontiac, was the first time I'd heard of any
automatic having a clutch, and the only reason I knew about
it was that it was misadjusted so that the transitions were
more abrupt -- and more noticeable -- than they should have
been, and I noticed six state-transitions instead of the
three I'd expected (the clutch never engaged in first gear,
so the transmission had a total of seven states when in
"drive"). Now I'm driving a 1990 Honda, and haven't found
out the details of the transmission, and the transitions
are smooth enough that I could easily believe I'm simply
not noticing clutch/torque-converter transitions or
that it has no clutch.)
In the "sport" setting the shift points are a
bit later -- the engine almost never gets up to 6000 RPM
in "economy", but winding it up that far is a pretty nice
option to have on a short merge-apron at the end of a
tight ramp -- so perhaps if I drove like a peak-testosterone
17-year-old drag-racer-wannabe the mileage would drop way
off in "sport" mode, I dunno -- I'm not going to start peeling
out at traffic lights just to find out. But for folks who
drive reasonably, I wonder whether the difference is not
so much "performance vs. economy" as it is "remind you subtly
of a sports car vs. feel as though you're being
good even if it costs more gas".
Interestingly, other aspects of the car's performance
feel more "sporty" in sport-mode as well. I'm not sure
whether this is purely psychological (my guess), or perhaps
an actual subtle change in the steering since it is, after
all, a front-wheel-drive car, so changing the transmission
might conceivably affect handling. Again, I wonder.
But if (with the way I drive) there is no fuel penalty
to using the "sport" switch, and not a really huge penalty
for using so-called-economy mode, I think I'll start switching
between the two modes depending on conditions and situation.
It turns out I prefer some aspects of the feel of "economy"
mode and other aspects of "sport" mode, and as long as
switching between them while the car is in motion harms
nothing, I'll take the best of each. (In particular, cruising
at [mumble] MPH over the speed limit feels more comfortable
in "economy".) And my guess is that the switch merely signals
an embedded controller to use different constants in its
algorithm, not to make an immediate change to the mechanism
when the button is pushed, I think it shouldn't
cause increased wear or other damage. I hope.
Of course I'm still left with a lot of guesswork. If more
concrete clues fall into my lap as a result of my posting
this, I shall not be unhappy about that. Or other guesses
than mine, for that matter. :-)