The so-called "Sport-Mode" test was thought up by some clear thinking E46 M3
enthusiasts on the Roadfly Message Board. This is a subjective field test
and theoretically can be used to show that installing a stick shift pedal assembly
into an E46 M3 with SMG will still yield maximum commandable engine power.
The idea is as follows...
The E46 M3
has a "Sport Mode" button on the dash. What this button does is change the response
curve of the DME to throttle pedal inputs. With the Sport Mode engaged the
throttle pedal feels more responsive, in that over most of the range of travel
it takes less pedal motion to command a given increase in engine power.
There is no change in maximum commandable engine power however, and this is a
very important point. Once the throttle pedal is fully depressed, the interpretation
by the DME is the same. Thus the two throttle pedal curves "converge" at full throttle.
This is displayed in the following graph which includes throttle pedal data obtained
by Akbar Khan:
Anyone who has played around with the Sport Mode button on the dash of an E46 M3 when at
part throttle has felt the sudden surge in acceleration as the DME effectively reads
an increase in throttle pedal command. This effect is quite noticeable.
So, if installing a stick shift throttle pedal in an SMG M3 really does lead to only being able
to command say, 97%-98% of full throttle, then if you were to take an M3 with such a configuration
and push the Sport Mode button in and out while at full throttle, then a change in the acceleration
should be felt. This is because the DME would, by this hypothesis, not really be reading full throttle,
whereby one would still be in that portion of the throttle pedal curve where there is a difference
between Sport and No-Sport.
Field Test Reports:
Most all users who have conducted this test, including this writer, can not discern any change
in engine power when engaging/disengaging the Sport Mode button when at full throttle in an
SMG E46 M3 with a stick shift throttle pedal. This would seem to indicate that the stick shift
pedal supplies sufficient electrical output when fully depressed for the DME to interpret a full
throttle command. This would lend weight to the theory that the full throttle threshold of the DME
software is set at some electrical pedal output below the maximum output capability of either the
stick pedal or the SMG pedal assemblies.
Possible Test Problem:
The sudden surge in acceleration that users feel when depressing the Sport Mode button
is at part throttle, and usually near the middle part of the pedal travel range.
This region is highlighted in the figure above by the green ellipse, and it is clear that
in this part-throttle regime there is indeed a large change in the DME interpretation
of the throttle pedal command when the Sport Mode is engaged. The software essentially "jumps"
from one curve to the other across a rather large gap. The size of this gap is what is
felt through the seat of the pants when depressing the Sport Mode button.
But for the interest of the "Sport Mode Test" the concern is in the region of 97%-98% throttle. This
area of the curves is delineated by the orange ellipse in the figure above. Here it is apparent that there is
not much difference in the DME interpretation of the throttle command regardless of whether
the software is in Sport Mode or not. In other words, if having a stick shift throttle pedal in
an SMG equipped M3 causes only a 97-98% throttle command to the DME, even with the pedal fully depressed, then
activating the Sport Mode at full throttle will cause the software to "jump" across the rather small
gap between the two curves near full throttle. For the test to be conclusive one would have to
be able to subjectively feel the change in engine output caused when the Sport Button is engaged
in this upper range of the curves. And since the difference will be much smaller than what most drivers
will be familiar with (from experience with depressing the Sport Mode button at part-throttle),
it is unclear if the difference would really be felt all that readily. Of course one could argue that if
it can't be felt then does it really matter?