335d at the Track
I can't say I am anything but a raw novice at the track, having been with my D to Summit Point Jefferson Circuit just once last September. That involved 4 track sessions of somewhere between 12 and 15 minutes each and one wet skid pad exercise (which I hated but really need). The first two track sessions were dry. The third it was raining heavily and the fourth it had stopped raining but the track was still quite moist.
The limiting factor for the car in my case was myself and the OEM RFT. The outside rib of the front tires got scrubbed some, and when things got wet those scrubbed tires were really slippery.
OK, enough of the downside.
My D, which then and at the present time has no tune job and only one change in the suspension (Bilstein B6 dampers all around). Jefferson Circuit is a short circuit (1.1 miles) with two straights that alllowed me to reach about 100mph and a shorter straight of about 80-85 max. As mentioned I was the limiting factor in the turns. Certainly others even in my newbie group were better. But if I exited the turn in the lead, no one (not even the M cars) could catch me on the straight. The torque was amazing. For a longer track of course the results would be different. As far as handling, I could not reach the limits of the largely stock suspension. Someone more gifted/talented certainly would, but I thought the car (except the tires) handled quite well.
Having said all that, it has been 40 years since I drove other cars fast in Germany ('71 2002 and '70 911E), so I can't really compare how the D handling compares to the other BMWs of modern vintage.
Quaife LSD w/VAC finned diff cover, M3 Rear SF Bushings, M3 sways & M3 OEM Susp Front/Rear Cmpnt Kits ('cept strut brace), GC Caster/Camber Plates, AC Schnitzer M3 Sport Springs, JRZ RS1 dampers, JBD 100%, Goodrich SS brake lines, non-stggrd APEX ARC-8 18" wheels with Nitto Motivo tires (winter OEM 17" wheels and Blizzak LM-25).