u/initiali5ed

1 gallon =4.546 litres
1 litre = 9.5kWh
1 gallon = 43.187kWh
7.4 mpkWh = 318mpg

I was kind a cheating as I started at 500m up in the mountains. It’s the highest I’ve ever seen in this car. I usually get more like 3.5 mpkWh (150mpg), this trip I averaged 4.2mpkWh so 180 mpg

If you really want good efficiency you need to go electric, it’s a whole different league to what you can do on petrol or diesel.