-Anecdotal, but indicates there's a certain honour among thieves - if you volunteer to visit inmates in Norwegian prisons, you get a parking pass to keep prison staff from having your car towed or bike removed while you're visiting.

An inmate advised me that I should just leave that pass on the windshield at all times - as it would be more effective against theft than any immobiliser.

I did leave it in place, and a few months later, just about every car parked curbside down my street had had its stereo and valuables snatched - except mine.

Now, obviously, this may have been a result of my stereo being pretty basic, though of recent manufacture from a renowned brand - but I like to think it was because of the visitor's service pass.