Pete...interesting comments and engineering ideas.
However in London city driving cars are often in the 0-1500rpm and I want instant response in traffic. For small engined turbocharged cars you do not get that response unless on boost. The fiat 500 2cylinder turbo was meant to be a warm hatch and it was compared to a panda 100hp (1.4 naturally aspirated, from a few years ago), both with 100hp on an auto magazine and was found wanting in stop and go traffic, off boost, in on boost rev range, throttle response, sound, and fuel economy on boost compared with the panda 100hp which has incisive throttle response in sport, has a far wider rev range, is more linear in responses, better fuel economy overall and sounds better. That was just an example.
For larger engines cars like your 156v6 possible in future there will be electric add ons for all cars to made better gas mileage and more environmentally friendly we will have to see.
For the current Giulia engine I am sure I read articles that there is a 4 cylinder hybrid electric/gasoline engine setup already designed and built but we have not heard anything about it for the Giulia yet. It was meant to have 350hp and fill the gap in hp between the 4 cylinder and v6 engines. The v6 hybrid setup was meant to kickstart the v6 coupe before it was cancelled and produce 600hp in bursts.
The Giulia's are already electric ready with their drive by wire brakes that auto engineers suggest are relevant once electric motors are installed on the front or rear axles.
Maybe this technology and the hybrid v6 engine will first debut in the Maserati Alfieri which will use the Alfa v6 engine modified, if it makes it to production.