I have to say the stop start system on my CLS is my only complaint with the car.
It cuts out far too early, I mean if you are turning the car and stop before reversing back the engine cuts out literally as you are selecting reverse.
Only this morning my missus was coming into the drive behind the little Mini I’m working on and being cautious not to hit the Mini the Engine cut out twice.
A total waste of time as far as I’m concerned.
Looking at one of the reviews of the CLS this also was a complaint.
It wouldn’t be quite so much of a nuisance if the time was extended to around 20 - 30 seconds before cutting out, I could live with that.