The SR22 is the most produced light plane in the world, and many of Cirrus’s sales are to return customers. Cirrus is just really good at adding enough new features to its latest models that a lot of existing Cirrus owners find they just have to upgrade to get the latest cool stuff.
The G6 might be the best example of the strategy to date. Even though the airframe is essentially unchanged (I’ll explain the “essentially” part of that statement soon), the G6 model is a huge upgrade. I’ll end the suspense. It’s the avionics.