If you did it the way BMW wanted you to you'd tap the holes under the sport seat to accept the proper "bolt." Self-tapping will work, as you found out.
Originally Posted by yappering
After trying many screws this is what you need for the sport seats with that adjustable thing in the front.
Size 14 - 1/2 inch long sheet metal screws. These are thick enough to actually screw into the holes and not too long to interfere with the seat adjustmant.
I hope this helps.
Screw - part # 07 14 9 169 302. M6X12 T30 You need two min for the front (there are 3 holes).
John in VA
'85 325e - RIP