Back in the 90s, I bought a Ford Granada. This was a big, dare I say it, American-style saloon car with a big thirsty engine. It even had a bench front seat and a column gear lever.
When cleaning it one day I found a mysterious hole in the side of the boot (trunk) which led into the opening behind the fuel filler door (It was the type that you open a little door and the filler cap was inside.
I asked a friend where I had it serviced and he told me that some previous owner was probably stealing petrol. Apparently, there would have been a pump fixed on the wall of the boot. The driver would go into a multi-story car park and find a car that did not have a locking cap. He would park alongside and pump out a few gallons. In many cases, especially with company cars, the other driver would not even notice.
“Locking gas cap”. Now there’s an idea I’ve not heard in a long time … a very long time.
I can’t say that I’ve seen one of those since maybe the 1980s. It is pretty universal on cars sold in the USA since maybe the 1990s that the door over the filler compartment has an integral lock that engages when the whole car is locked. It’s a pretty flimsy arrangement usually; one that a little vigorous prying will easily defeat at the cost of damaging the filler door and surround. But it is there and stops the barely honest.
But locking gas caps? That’s practically horse-and-buggy stuff.