Porsche has changed the 911 body, quite radically in fact, if you side-by-side anything 1980s or before with 2012 or later. But what Porsche does very well is

Porsche has changed the 911 body, quite radically in fact, if you side-by-side anything 1980s or before with 2012 or later. But what Porsche does very well is introduce new platforms every few years. It's still a 911 but a new generation, that generates excitement and new sales. Then a few years into each cycle, it releases various sub-specialties and performance variants -- the RSes, GTs, Turbos, etc. Yes this often means at the very end of a platform's life sales drop (in anticipation of the next version) but overall its clear that Porsche has been extremely successful with this release model, which I think the other German carmakers emulate, like BMWs 3-series.