"Efficient Dynamics" is not exclusively reserved for a start/stop system.
The term is also valid for engines with "2nd gen direct injection", for "brake energy recuperation", a technique used to brake the car with the alternator by loading the battery primarily in situations when you intend to drive more slowly (this is the reason why you have an extremely expensive AGM battery in your car...). It is also used for the "very useful" shift indicator in cars with manual gearshift.
BTW: The newer 4 cylinder E89 models (20i, 28i) indeed have s start/stop automatic
Best regards
Mick