One question to the people who say how many mpg they get: where are you getting the figures from?
My car gives am MPG readout of the current trip, but that varies a lot, especially on short journeys.
The motorhome doesn't have anything like that, and for years the fuel gauge was unreliable, so each fill was written in a book, with odometer readings.
The odometer is not accurate either, but I calibrated that with GPS track data.
The fuel gauge is fixed now, but old habits die hard, so the fuel record continues.
In the motorhome, the cruise control is much more economical then my right foot, but consumption isn't all that much different for urban or rural, short or long trips. These make a big difference in the car.