To illustrate the point I’ve just driven in EV mode only with no petrol use at all and the petrol range has dropped by 10 miles I’m confident that my maths are right but there’s a small degree of guesstimating that will be tidied up when I fill up.
As I mentioned yesterday your petrol range with a full battery is 350 miles. You then go out and do 10 miles purely on electric, your petrol range will now show 340 miles give or take and so on…
Therefore, what we think is the petrol guage showing range on petrol, is not the case. Rather it is showing the total range the vehicle can travel including battery range available.
It took me a while to work that out.