I checked out those .capx files you linked me and while they were informative, they haven't led me to a solution for my problem. Although they did make me learn about Families, so that was good. Thanks.
Upon reflection, I was thinking that maybe my initial test project wasn't representative enough of what I want to accomplish, so I've replaced it with a new one which is much more in line with what I'm trying to do.
Download it here: https://www.dropbox.com/s/lrxpi6ym5niysf0/CarSelfDetection.capx
If you can't download it, here's some screenshots.
Layout (The car facing left is the one which accelerates)
Basically, there's a bunch of cars and one of them starts to accelerate (instance variable crashed == false). Every tick, for each car in the layout, I check the area in front of the car and if it is not overlapping another car at offset then I accelerate. If there is a car detected then I stop. Unfortunately, as you can see if you run the project, the car does not stop.
How do I make the car stop?