Went for a drive with an empty battery.
Ran the battery down to --:-- and then pressed the fuel trip reset gauge when the ICE started. Atechnique used by others for this comparison. This was to do a 25km, 60kph bit hilly and bit windy test with only petrol supplying the energy. Started out for first 3km at 80kph. In the 60kph region, there was a downhill section and then an equivalent uphill, with a town section and 60kph max for about 22km.
Pics, drum roll :-
I was quite surprised as well.
No nasty stored solar power to confuse the petrol numbers.
Speed plays such a big part in any comparisons. Equivalent longer journeys at highway speeds has only returned an average of about 8L/100km at 110kph with passenger and some luggage.