Nice to know that Morgan are looking after me and want me always carry around that 16litres/12kg of fuel that I can't use in a light-weight sports car

Doesn't mean you can't use it, just you have to be confident about how far you can get on 16litres..... (I would have thought at least 100miles allowing for a bit of unusable volume at the bottom of the fuel pick up)
On older vehicles, you can alter (bend) the float arm to make the reading more accurate - not sure if possible with a more modern car.