ian pats lpg tank in his volvo
as for teh post above, I've not lauged so much for a while. If petrol evapoarted and vented so quickly every car would stink of the stuff.
Ground temperature doesn't vary that much irrespective of above ground temp. Look at very frosty mornings, if all liqued unedr water froze the whole drainage syetem woud be a stinking blocked up mess.