Apple Car Play Retrofit
 

I am in the market to buy my first Audi. I would really like to get a 14-16 Audi A6, but am considering a 15-17 A4 as well. One major factor in my purchase is Apple Car Play. I know it was supported out of the box starting in 17, but I found multiple articles that suggest it was going to be supported in 15 forward on some Audi Models but I can't find any more details than that.

Can anyone tell me with certainty whether any of these models can be retrofit or the MMI can be updated to support Car Play.

2014 Audi A6
2015 Audi A6
2016 Audi A6
2015 Audi A4
2016 Audi A4

Also, does Car Play support infer that Siri Eyes Free is also supported?