Having said that, most of the time I never use it - fuel consumption over the past year has been about 2 litres (in 9000 miles) BUT it is the get out of jail card when the battery is depleted and with that you're quite able to run the battery to its last few miles of range without worry of becoming stranded.
John
Doesn't fuel go off? It certainly does in my lawn mower if I don't use it for a couple of months. I would think you needed to use a tank every couple of months at least just to make sure the petrol is not too old.