When gasoline prices rise, so do the sales of locking gas caps. When drivers start worrying that the unscrupulous may come around in the dead of night, looking to siphon precious gas out of their tanks, they turn to locking gas caps. Locking gas caps are exactly what their name implies: gas caps that can be secured with a key. Most gas caps just screw into the opening to the tank. Locking gas caps come in two kinds: they will either be secured and locked with a key, or a key will release the catches so the cap can come off.

The kind of locking gas caps that lock when put in place and release with a key are the older models. Although they are effective, the disadvantage is that if the key is lost or misplaced, the cap cannot be removed. The driver will have to call a locksmith, who can make a key from the lock.

The other type of locking gas caps must be both locked and unlocked with a key. If the key is not available to lock the cap, then the gas cap works like an ordinary one. Most locking gas caps come with two keys, but the cap that must be locked with a key better prevents accidents from happening.

Locking gas caps also prevent vandals or angry teenagers from putting something like sugar or bleach in a gas tank in order to ruin it. People whose gas tank doors lock automatically may not need to worry about purchasing locking gas caps for their vehicles, but drivers who have standard gas tank doors may want to consider it.

Locking gas caps are available in most auto parts stores, in discount stores and online. They are sold by make and model, so a cap that fits one vehicle may not fit another one, even if it is by the same car maker. Drivers should always look for the cap that is specified for their car. Locking gas caps cost in the US$14-$25 range, depending on the manufacturer and car's make.