Had success to get the CSR to drill down to the $25/5 months deal. Just say 'naw, that's too much, just cancel' at each step down the price ladder until you get offered the $25 a month (plus taxes etc, so $26.86 total for 5 months) deal.
Previously I had $118.41/year X2, they wanted $218.55 and $150.21 to renew the two cars. That wasn't going to happen.
Note this is for SiruisXM Select, not all-access, and I don't take the streaming service since most places I work at, there isn't any data service.
I got that rate for both cars on the account. It won't auto-renew at that rate, of course. But for a 5 minute phone call, definitely a good ROI on the time spent, and since they mail me a bill anyway a month prior, it's not hard to put an alarm in the phone to call and negotiate the cost back down.