Originally Posted by CanAutM3
Actually not. Some seats have the adjustable lumbar support and side bolsters, some don't. Having been in the non-adjustable kind as a passenger, I can attest that you move quite a lot in them.
In my car I do have the adjustable kind. For the track, I completely deflate the lumbar support so I lay deeper in the backrest and have more contact with the side bolster. I then tighten the side bolster until I am nicely snug.
I then use the belt tightening technic specified by OC3 and Estoril Blue.
To clarify, I was saying there is no such thing as comp package seats. Yes, obviously BMW offers both power (with the adjustments you describe) and manual, but the seats are the same shape, size, etc. I don't find the adjustable bolsters or lumbar make a bit of difference in keeping me in the seat on the track.
It would be cool if they offered a true "sport seat" option a la Porsche and others that would be more in line with their Performance seats, or better yet, the seats out of the CRT...