How do you get a broken locking gas cap off?

To remove a broken locking gas cap, start by using a pair of pliers to grip the cap and turn it counterclockwise, if there's enough of the cap exposed. If that doesn't work, you can try carefully prying it off with a flathead screwdriver, but be cautious not to damage the fuel filler neck. In some cases, you may need to drill into the cap to create a hole, allowing you to use a screw extractor. If all else fails, consider contacting a professional mechanic for assistance.