I wish they would broadcast the "Nation Wide Series"on the radio like they do with the "Sprint Cup Series".

Also, anyone know what the XM radio Nascar channels are or are they on Sirius?

MRN broadcast all the Cup, Nationwide and Truck races..

http://www.racingone.com/mrn_schedules.aspx

Michigan Radio MRN affiliates are:

WCSR-FM 92.1 Hillsdale MI
WOBE-FM 100.7 Iron Mountain MI
WIMI-FM 99.7 Ironwood MI
WJMS-AM 590 Ironwood MI
WKHM-AM 970 Jackson MI
WITL-FM 100.7 Lansing MI
WVFN-AM 730 Lansing MI
WMUS-FM 106.9 Muskegon MI
WKBZ-AM 1090 Muskegon MI
WHLS-AM 1450 Port Huron MI
WHLX-AM 1590 Port Huron MI
WSAQ-FM 107.1 Port Huron MI
WPHM-AM 1380 Port Huron MI
WTWS-FM 92.1 Prudenville MI
WILZ-FM 104.5 Saginaw MI
WYLZ-FM 100.9 Saginaw MI
WKNW-AM 1400 Sault St. Marie MI
WMLM-AM 1520 St. Louis MI
WKJC-FM 104.7 Tawas City MI

Not every affiliate broadcast every race.. but you can get them all on Sirius NASCAR channel 128.