According to the Owners Handbook of my 2007 4/4 (which seems to cover the whole model range up to and including the Roadster 2 & 4 seater) the fuel tank capacity is quoted as 55 litres at empty for all models. Anyone brave enough to run dry to find out??
I don't like filling ours as there is always a strong smell in the car. After dumping fuel in a Tesco filling station I had the dealership check it out but it still pongs if filled.