Except in the case of accidental spillage, it is probably safer with fuel in, than 'empty' which is usually explosive fumes of course. A friend of mine used to demonstrate this by putting a cigarette out in petrol. Mind you I was never close enough to verify it ... I found I can run really fast when necessary.

I have just started using trains again after twenty odd years. I can get into the nearest large town 100 km away for about $5 return, do some shopping at much cheaper prices and the saving there and the petrol saving add up to at least $100 a month which is great news on a pension. The trains are never full, I wish more people would use them but they prefer to pay $25+ in petrol and drive alone just for the door-to-door convenience. Oh yeah, the train is actually 15 minutes faster than driving to the same place!