Surely it rather depends on how big the tank is???
I have noticed that these days new cars seem to have bigger capacity tanks
My LandRover (Freelander) had a piddling little tank and would only do around 150 miles/ tank before I felt "insecure" about the gague reading. Typical mpg was 30 on a good (motorway) run.
I now have a Meriva 1.4 Turbo and that does 40 mpg on the Mway. Dunno the size of the tank but I have done 200 miles and it has only dropped to near half way on the gague
The motorbike (650 BMW) will turn in 68-70 mpg
5 Precepts of Buddhism seem appropriate. Refrain from taking life. Refrain from taking that which is not given. Refrain from misconduct. Refrain from lying. Refrain from intoxicants which lead to loss of mindfulness