Another bad of the locking gas cap: I bought one of my GP's from the Pontiac dealership back in 2004, and at that time, I purchased 2 locking caps with the tethers, they were for sale right at the dealership. I bought them and still use them. But in the winter, I have had snow and ice get under the fuel door on the top of the gas cap and then melt, and refreeze. That prevents the key from being inserted in the cap. Hasn't happened too often but it has happened to me.
One plus of having a locking cap is that is could stop someone from randomly removing the gas cap and pouring foreign objects or liquids in your tank. I belong to auto tech/mechanics groups and I read that it has happened where cars were brought in with the engine seized up from a vandal pouring sugar into the gas tank. A locking cap might prevent a vandal from doing that.
