I think UI's are the main factor in the average user's perception of quality. While re-designs may be annoying to old users, they're necessary to avoid potential new users thinking the product is outdated. The UI should always look brand new.
What separates fog from client-side is the concept of hierarchical fog nodes. You could imagine the car's sensors as the edge devices and the car itself as a fog node. The whole fog hierarchy would be something like: edge devices - cars - intersections - ... - cloud. At the intersection level collisions could be avoided by processing data from local sensors and warning incoming cars.
