My first attempts at toggling between PIC and Radio control automatically have not gone well. I figured that the PIC could know from the proximity sensors that it was inside the maze. There seems to be too many variables.

If I were to use a light sensor to distinguish, which sensor and at what wave length makes sense. Remember I am imagining the cars to be racing - going fast even in the maze. This set up would be in a middle school gymnasium - a basketball court maybe. If I could imagine making a maze out of BIG cardboard boxes with roofs I could use simple light detection. But I don't see how to make that elaborate a maze. Is there a light detector that does not see ordinary ambient indoor lighting, but does see some kind of special light source? Could I run a string of these light sources the length of the maze? Inversely I could run a string of these light sources outside the maze where the cars would see them.

Thanks for your attention.

Ken