Why is the rum gone?
Join Date: May 2012
Location: United Kingdom
County: Greater Manchester
try parking it somewhere else? With the filler against a wall, or other obstacle.
Or park it in the same place and figure out which night they are most likely to strike.
Then lie in wait.
they will probably be kids, and only one or two of them at most.
Almost certainly be before midnight.
Leave your tank almost empty so if you miss them you lose as little as possible.
Leave a trail of nails or tacks around so they might lose a tyre whilst doing the deed (if possible) and be prepared to block them in in order to beat the crap out of them. (If they do this regularly they probably have a pump/syphon system in place so they just pull a car up next to yours, pop the filler cap and empty your tank from the passenger seat of their vehicle)
depending on how advanced they are you could just park your car the other way round, if the filler is road side they might have stuff to pump the fuel out of your car from another vehicle, which isn't set up for pavement syphoning, or they might just have a bit of tube and a can which is really easy to use from the pavement (because you can hide easily) but not so good from the road side.
Non of this is from experience ;-)
But I have been around the block a few times.