In normal use I used to get about 35mpg from a 1.3 and 22 from a 1.6. I'd do a brim to brim measurement and if you are lucky you might just find that the gauge is not all that accurate...
Good luck
The gauge could well be completely wrong, but that doesn't change the fact that I only get 80 miles from 12 litres. You were getting 35mpg from your 1.3, so mine should be there or there abouts. Perhaps I ought to take the upright piano off the roof rack when I drive around
I'm only a little way off, and I'd been told that she was running a little rich - perhaps it had always been like that but I'd never noticed prior to petrol going over a pound a litre.
If one good thing comes from this thread, it'll be a useful matrix... just don't use my car as the basis for the 1.3 Fulvia data Sparehead