Wanting to know the amount from a tank is silly. Some people brim their tank, some don't. Some pumps cut off early, some late. It is completely useless. But if you measure exactly how much fuel you add, and know exactly how far you have traveled, it gives you an accurate economy figure.
In any case, I've had my 2.5L AWD CX-5 in Winnipeg for just on a year now. As of my most recent fill up I have done 7528 km using 871 litres of fuel, for a final figure of 11.6 L/100km. That is 20.3 MPG. Now that is not great. But there are a number of reasons my fuel economy is that low...... lots of short trips, lots of heavy traffic, very cold winter, lots of remote starter usage, and a very heavy foot on the gas pedal. For the small handful of longer highway trips I have done, I easily manage 8L/100km (30MPG) at 110 km/h (70mph).