[albertw]

I took my m240i out for the first trip to the twisties. I'm looking for an explanation for some odd behavior.

First, the good. Steering feedback at the traction limit is no worse than the 01 Z06 I drove for 16 years. Based on all the negative press, that's better than I expected. In steady state cornering at low speeds (50 - 60 mph), as the limit is approached the car is neutral - front and rear slide equally. I don't know if it would be that nice with the staggered setup that comes with PSS tires, but I ordered all seasons to get the square setup hoping for this behavior, and I got it. The lower corner speeds at the limit is a nice bonus on the street. Yay!

I wanted some of the nannies on for my first spirited drive so didn't try DSC Off.

In Sport+ I could add some throttle from a gentle 4-wheel drift and get the read end to step out predictably, without altering the cornering line much. Again, nice. If I accelerated from below the traction limit, both rears dug in and drove the car quite hard out of the corner.

In Sport I could also get solid acceleration if I started from below the limit. What was odd was if I tried to step out the rear from a gentle 4-wheel drift. The car would not accelerate much nor was there the desired change in the cornering attitude, but traction shifted dramatically from all four wheels to what seemed like only the outer wheels. Since they couldn't handle the load, the car immediately started to run wide. In about 2 seconds it would go from running comfortably in the middle of the lane to the edge of the lane. If my observations are correct and that's really what the DSC is supposed to do in that situation, it seems odd to me and possibly a bit dangerous.

This is of little practical importance to me as I'll likely spend most of my twisty time in Sport+ or DSC Off (and there's likely an LSD in my future), but I do like to try to understand what the car is doing.

Comments?

[SteveInfante]

It's operating exactly as designed. The DSC is poking its nose in when you are in Sport and not Sport+. It's good to see an enthusiast enjoying their car.

[CP911]

Originally Posted by SteveInfante

It's operating exactly as designed. The DSC is poking its nose in when you are in Sport and not Sport+. It's good to see an enthusiast enjoying their car.

Correct. Sport still has full DSC intervention while entering Sport+ also enables DTC. DTC is a mode of DSC with reduced intervention, allowing some wheel spin and rear end step out.