Why my 2016 BMW 750i gives me only 7MPG

[ninox14]

Hi, I am very new to this. I recently got 2016 750LiXdrive G11. It shows that it only gives 7MPG. I drive very nicely, not aggressive or anything. There is absolutely no leaks or smell of a gas. Engine is perfect, you can barley hear it. Car drives amazing, without any problem. I tried to reset the MPG, but again it keep drooping as I drive. Just no way I get only 7MPG.
It is also very weird that it says that my average speed is 6.5MPH and 7MPG consumption. Could something be wrong with the software?

[Markr]

Sounds like you have a sensor issue, but just to prove that, fill the tank, reset the odometer to 0, and drive 30 miles or so. Has the fuel level moved a little or significantly, and if you refill the tank, how much have you put in?

If you really are doing 7.5mpg, 30 miles will be 4 gallons (UK) and your fuel level will have gone down by c. 1/4.

Also, do the maths, divide the 30 miles (or whatever you do) by the amount of fuel used to top up and that will give you your true mpg.

It is more complex here in the UK, because whilst everything is quoted in miles per gallon, we both sell and dispense fuel in litres, so we have to divide litres by 4.546 first.