Although not a new city owner but as per my understanding the car computer excludes the reserve fuel while calculating the cruising range.
Like as you said that you filled it last time when there were only 16kms remaining on the dial. after these 16 kms the reserve light would switch on and the 7 litre reserve petrol would start burning.
This is because the manufacturer never recommends taking the car to the reserve light 'ON' limit very often. They rather recommend keeping the fuel tank at 1/4th level.