All you can give are the figures you produce and that’s what’s important. If you have had your car for a while you will know, roughly, with your particular driving style, how far you get on battery only on short journeys or on the motorway and the same on petrol only or a combination of the two. My daughter has a phev and gets 30 miles on electric when on the motorway and, strangely, 25 miles about town, the reverse would be expected. She is getting about 70 mpg but is almost always driving in electric mode.
Not sure if we are the typical PHEV user we tow a 1500 kg caravan on average more than 1500 miles a year plus make frequent longish drive to see the grandchildren, we tend to charge up at home or the odd sneaky top up at Tesco’s
The last time since getting back from a towing holiday we filled up 1st June, since coming back we have been up and down the motorway covering 1023 miles to date, at lunch time we filled up at Asda’s 19.52 litres @ £1.287 (£25.12) plus since the 1st June £11.40 @ 0.05 kWh in electric total cost to cover 1023 miles = £36.52
Tell me I am wrong = 163.94mpg
Unfortunately I have suffered a brain injury and occasionally I get confused and often say the wrong thing.