the difference in the M button is rather subtle at times...
I can definitely feel a difference.. and truthfully, I do not prefer to engage the M button.... in my opinion the throttle response is WAY more sensitive.... and the boost too agressive with it on. I typically leave it off unless I am going to attack a twisty road or on ramp and want a little extra omph.
for track driving.. I normally don't use it.
For autocrossing I DEFINITELY prefer it off... on small courses, even where it should reduce lag, i find that the boost coming on stronger makes it more difficult to control rear wheel spin.
I actually drove at an autocross a week ago... it was a high speed event, with FTD in the 86 second range.
course map
http://lscbmwcca.boards.net/index.cg...#ixzz2Y0BTo7Sp
results
http://lscbmwcca.files.wordpress.com/2012/07/event-5-july-132013.pdf
course video - NOT my video- NOT me driving.. Video is for illustration only.
[u2b]
http://www.youtube.com/watch?feature...&v=Di9Y2_kf7Eg[/u2b]
For the first time... at this event... I really felt the M button actually helped. See the course map, and note the FOUR long slow speed 180 degree plus corners with a long straight afterwards... The very first severe hairpin turn to the right is depicted on the map as a 180 degree turn. In reality, it was about a 220 to 235 degree turn, taken in second gear, and the time to negotiate it definitely resulted in the car getting OFF the boost..... The final turn, shown as a 270 degree turn was a decreasing radius turn.. 180 degrees entering.. then suddenly sharply decreasing radius for the last 90 degrees and then a blast to to the finish after a quick jog left... With the M button on, the car definitely leapt out of the corner and onto the straight with more ferocity. it also showed in my lap times, which improved in the afternoon when I tried the M button on for the first time in awhile.