I think SiriusXM messed up in my favor.
I had the cheapest package in my van, but the new car came with a 3 month trial of all channels. Once the 3 months were up they were supposed to turn off the van and move my cheap package to the car. It's been 4 months and I still have both cars with the full package and they haven't charged me for the full package, just my cheap one.