Re: Rule of thumb
"The bigger the engine and the....." - the MORE fuel it uses at IDLE . Many car manufacturers offer automatic stop/start in Europe - they will have researched it.
Your evidence is .....? No, thought not
Back of spreadsheet calculation using very rough figures.
Starting amps 1000, time 2 secs = ~7watt.hrs - that's really not very much at all. On the other hand I can watch the fuel drop at idleon the trip computer.
And BTW, I've a holiday home in Switzerland at 1800m (5800ft) and the car ( VW turbo diesel ) starts fine even at -15C.