There are a lot of times when it’s useful to be able remotely turn something on or off. In this instance, my son has a small Power Wheels car. I wanted to be able to turn the car off if he drives too far away, or in the wrong direction. So I designed a simple remote kill switch, which lets me turn the car (or anything else) on and off with a remote. As an extra safety feature, if the car goes outside the range of the remote, it will automatically turn off.
See the project on Instructables: instructables.com/id/Remote-Kill-Switch/