This one is well documented in the manual and here, but for anyone who has seen another E90 on the road signal right, then left, then right again, it is because they don't know how to cancel the turn signals.
To cancel the turn signal, you
don't push it the opposite direction. You push it slightly (not beyond the resistance point) in the same direction as the blinking side.
The blinkers are intuitive once you get used to them and now I don't like driving cars with "normal" blinkers.
