I can understand why it can't change because of the GPS time signal (GPS does send time, but its always UTC - those satellites don't send out special times for particular time zones lol)
On the other hand, my computer (which also receives time in UTC) knows when to change the clock because it also knows that I've told it its UK... if I set it to a US locale it would change the clocks when the yanks do it (which is this weekend coming).
My Golf is also told that its UK - which means the time and date format, the speed and fuel readings and headlight dipping direction are all set to typical UK values... so why not BST/GMT swap overs?
Again, as before, the technology is all software, the car is capable, they just can't be bothered to give you a well thought out product but still charge you thousands for it.