Did you get an "over writing previous address" error or something like that? If so then I bet the Lines in the PBP *.inc file need commented out. But setting the fuses in thae inc is good too, personal preference kind of thing.

Light sensors. You should get a lot of feed back on that one.

Off the top...
I think you said that the car was going to look for a light. You may want to think about some small solar cells. Being a voltage is produced the ADC could read them directly, well it should if it is not so low a voltage as to not have a good resolution.