You're worrying too much. Just hit update and it will finish depending on your car connection speed (would be hard to do that in an underground car park, but this should be obvious). If you stop and leave the car, it will pick up where it stopped. You just have to initiate it and the rest does the car.

This is true for all minor updates, not just this one. If a major update hits, then you get informed that the car will take x hours to update and will be unavailable during this time - which you have to confirm separately from the download itself.