There isn't much more you can hear on XM/Sirus that you can't hear on your local radio station. The days of the dominant Top 40 station are gone. There used to be three or four that played the latest music, now there is only one. Radio Stations now are after the niche audience. The formats now are classic rock, country, hit music, and talk radio. The formats that have become popular recently are classic country and sports talk radio.
The car talk show that is on XM on Saturday mornings is probably the same one that airs on the current KAAY. America's Car Talk is the one that airs Saturdays at 11AM CT on the current KAAY. Really one is free to listen to and the other you have to subscribe. Why pay for it when you can listen to the same thing for free.
Thanks for the comment although I must disagree.
I can't hear the 50s, 60s and 70s the way XM does it on local radio. And that is large, large, playlists, authentic jingles, DJs with a style that fits the decade, features from the decade, i.e. "chickenman" and much, much, more. I have no interest in Howard Stern or Oprah. The money, in my book is well spent even though I only listen to a few channels. I think XM and Sirius have both missed the boat is knowing who there potential audience is. The last demographics I saw on XM had a definite skew to older adults. There advertising seems to be to a much younger audience. Perhaps that is who they see as their potential subscribers but I doubt it. XM,Sirius, and AM/FM radio need to understand they cannot out "jukebox" the Ipod. Their content must be unique. If it is unique enough and it appeals to the audience, They will even pay for it.