roadkillrob is of course correct, I have just one little thing to add..

The next platform refresh is expected in 2014. I suppose that's just a rumor - one version of the rumor had it at 2013, but that would still be consistent.

When I bought mine, he said they were on a 6-7 year cycle, which is consistent with other luxury marques; the caveat being that's a PLATFORM cycle, not really a "model" cycle. In between, BMW makes lots of changes all the time.

The E70 platform has seen several engine and transmission changes, some (VERY MINOR) cosmetic changes and a whole lot of equipment changes in that same cycle.

With Lexus (sorry, I'm still in recovery) there were only VERY VERY MINOR changes in that seven-year cycle. In the seven year life of the GX470, they upgraded the NAV graphics, added an (analog) AUX port (no iPod features, no control) and SAT audio as a factory option (it was long available as a $1000 dealer option).

Most luxury makers change their product more frequently mid-lifecycle; it seems BMW most of all. I'm still a little torn over this.

Either that, or I'm bitter about not winning the lottery so I can buy a new one every year.