Ok I will give you an example towing a 1500kg caravan back from the New Forest 181.7 miles from site to home,
13.6 kWh £2.04
Fuel 25.75 litres £35.77 (£1.39 litre)
Total £37.81, now covert that back to litres (37.81 divide by 1.39 = equivalent to 27.20 litre)
27.20 litres divide by 4.546 = 5.98 gallons.
181.7 miles divide by 5.98 gallons = 30.38 mpg.
Unfortunately I have suffered a brain injury and occasionally I get confused and often say the wrong thing.