There is only one way to be
There is only one way to be accurate when determining fuel mileage. And that is to fill the tank until it can no longer hold anymore fuel before you start driving and when you refill the tank. According to people in the gas pump industry, you will not get the same amount of fuel in your tank by stopping at the first click as you say. Depending on conditions with the fuel tanks and weather temperatures the gas pump, stopping at the first click is going to differ from one station to another. Filling to the top each time and dividing the number of miles driven by the amount of fuel put into tank is the only truly accurate method to determine gas mileage. My 2020 Lexus 450H is without a doubt the most accurate when it comes to stated mpg on fuel gauge vs actual mileage. If my fuel gauge shows 28.? Mpg, The true mileage will actually be 28.? mpg. I have owned over 40 vehicles and I have checked every tank for mileage the last 20 years.