Is Disney implying that they're going to create a vision system that registers guests' faces in a database, then changes the ride ending if that same face is recognized that day?
If that's the case, then... whoa.
I am rather suspicious about any ride profile variations. Look at what they did with Indiana Jones Adventure. The ride variations didn't seem to matter much and they won't fix the many special effects that don't seem to work. With the Cars ride, you'll just experience one or two variations that quickly get forgotten.