My speculation is that one of the newer updates allows storage of map tiles on the HDD, thereby reducing the amount of information streamed to the car and making load times seem "faster".
I read somewhere else on this board that the car simply does not have a LTE antenna, so it can't simply be "turned on" via software. However, I don't think anyone has been able to conclude whether the installed antenna can or cannot support HSPA (4G "lite") definitively.