The car I traded in was a 335d with sports suspension. It was great but perhaps a bit too hard on bad roads and would dislodge your teeth when going over the smallest pot holes.
When I test drove X3 30d M sport it had the normal suspension. It was a very good ride yet had good control, though if pushed hard it had a tendency to float a bit, but nothing bad.
When I ordered my 35d M sport I was advised to simply go with the normal suspension as the roads here in Switzerland are quite good. True but I also often go to Germany. Anyway after reading a lot of post I decided to go with the VDC. I HIGHLY recommend it! It is not cheap but if plan on keeping the car awhile and like to drive a bit hard it's truly worth it.
In order of preference I would recommend the following:
1. VDC - gives you:
a. normal
b. sport, with option of sport chassis/drivetrain, or chassis only (good on autobahns), or drivetrain only (pointless IMHO).
c. sport +
2. Sport - good control but not overly hard (like my 335d).
3. Normal - great comfort but maybe a bit unstable at high speeds.
It all depends on your driving style, but then again it matters not what your driving style or mood is if you chose the VDC.
VDC =
