Car lettering does serve as a purpose. In Formula 1 it designates tire compound. Can't say other motorsports is the same but I'm only doing for the look.
As far as the auto shut off, while I understand the theory of saving a minimal amount of fuel at idle, doesn't the constant start and shut off damage internals? I'm from the school of start up is the most damaging part of ignition. While I understand there I fuel, oil and warmed up engine block during these periods, a constant stop start has to be decreasing the life of some crucial parts along the way. Not to mention the delay. Many a time I've seen someone coming at me and I move out of the way. Can't say that 2 seconds from no ignition to start and acceleration would hurt but I'd rather not have my cars computer think for me in that situation.
With electric it'll be instantaneous, and I like that, but most of the stop start vehicles are SUVs and trucks. Not exactly shooting out of the hole to begin with