Dont knock the b11s they are great cars built around bmw best engine the 3.5 on the road tests up againts the 750 the b11 was top dog.As for the b12 too much can go wrong very expensive to fix my mate has a blue nice car but you have to be careful.
B11 only came with 261 bhp.
mahale cast pistons.
light alloy cyclinder head alpina large bore exhaust system loads more engine mods.
five speed manual or 4 speed sport box special alpina differential and limited slip diff.
alpina suspension gas filled shocks.
alpina light alloy wheels ultra light weight.
body coloured alpina front spoiler [no back spoiler]
alpina steering wheel front and rear alpina badges alpina dash plaque.
Total price on top of a 735se £11.900 PLUS VAT.
Hope this helps.
Cheers
Ryan