Your not driving it properly hahaha and them runflats dont help as it brings the traction light on all the time unless you disable it.
335d is not super quick as standard but when mapped its alot better and driven right it can pull from quite a few things.
Back to the miliage point of things i suppose its difficult to say what miliage makes sense for a diesel, if your thinking along the lines of a 320 then im guessing it would have to be alot but if your looking at a 335 then id say 20k+ would warrant a diesel.
E63 M6 - Matte Metallic Blue
, BC Forged HB29's, Eisenmann Race Exhaust - SOLD
Audi RS5 - BMW WHO?