Or, if you just want to do it the free and inconvenient way, pull the fuel pump relay from the main fuse box (usually under the hood) as you're stepping out of the car and put it in your pocket ...

Hidden ignition or fuel pump kill switches were once popular and could be installed quite easily. Today, many cars have anti-theft systems built in.

Hidden ignition or fuel pump kill switches were once popular and could be installed quite easily. Today, many cars have anti-theft systems built in. Car Doctor: Can I install a kill switch to ...