One of the perks that US military people stationed in Europe had was a reduced price on gasoline. Now I doubt very much that the price of gasoline was very high anyway, by today's standards, but still, it made it cheaper for us to drive all over.
The way it worked was that my dad could buy coupons worth 10 liters each at work. We then just needed to find a gas station that displayed a special symbol, that of the army quartermaster. Then we could buy gas just using the coupons.
Our routine was that my dad would order "quarante litres", which was about the extent of his French. Quarante litres means "40 liters" and it's roughly 10 gallons. He gave them four coupons and away we went.
But as the oldest, and the one that spoke the most French, I guess it was my job to make sure they didn't go over the 40 liters.
Well, one time they did, and my dad had to pay cash for the extra, and I was sure in trouble...