What does it do? The major highways are under nearly constant construction, not to mention sometimes there are accidents, lane closures, and other obstructions in the roadway. I am curious what would need the accuracy of a LIDAR map but is okay with one that's not realtime (and possibly wildly inaccurate).

The only thing I'm sure they use the map for is limiting the feature. They probably also extracted features like bridge abutments (where they might show up as a potential obstruction to the sensors).

The system is just a hands free cruise control, it still has an attention monitor and won't even do things like switch lanes: http://www.cadillac.com/world-of-cadillac/innovation/super-c...