I'm not up on my American cars!

2005/2006 models are already being designed in a lot of cases! The automotive industry is aiming to reduce the time for a new car to around 18 months, which is why you are seeing common platforms across brands/models, but it still takes longer than that in a lot of cases.

Aftermarket is a good place to start for new audio products, proving the idea, then OEMs usually go for optional or dealer fit units, and then into proper line-fit units, especially with this sort of product. It could go many ways!