Engine Start-Stop
a feature solely for MFR fuel consumption improvement then marketed to the consumer as a customer friendly feature.
It is not what I would say called for in regulation at the moment. As noted above, if the feature is active during emissions certification then it most certainly is involved and thus MFR can't allow permanent deactivation (only inconvenient temporary deactivation).
Eventually most if not all cars will have this feature someday. Features like this are not typically spread across all product platforms at the same time. Usually spreads to new product at re-design points and targeting areas that offer the most fuel efficiency credit (for the MFR). MFRs implement engine Start-Stop differently of course. So they can vary between seemless-ish to outright intrusive in operation. Sitting at a stoplight and some cars next to you are startling/distracting when the systems activates and deactivates.
So much disappoint...if only that effort spend on bandages like this were put to use in areas that could have larger impact.