Hidden fuel pump switch is going to hinder them as it will die 100 yds down the road or 20yds with a V8, then they got ta find it, an if ya got more an one they are stuffed.
You can do a very nice one with a hidden reed switch behind any plastic trim in the landy - activate it with a magnet. Great as there is no physical switch for a thief to find, and even if they knew they needed to swipe a magnet somewhere (f**k knows how they'd know that) they'd still not know where.
Possibly not great for Series and 'fenders as they tend to be all metal, but, for other classics it's a useful trick
