XM Traffic seems to have a lock with most in car navigation systems. Sirius does offer Sirius traffic, but seems to be so far only a few Chrysler/Jeep vehicles. FYI, both systems essentially provide the same information as the information is provided by Traffic, a Navteq company. The are other ways to access the information, but it depends on how much information and detail you want. You can't beat the integration feature unfortunately. The traffic information as well as road construction and accidents are available online at traffic.com. I myself access the condensed version on my cellphone. If you have Windows live mobile installed on your cellphone, the flow rate information is available, which is the road display with green, yellow, and red overlay. There is a short time lag, but then again I personally don't need to know why traffic is slow, just that its slow and where. I believe its also available on Yahoo to Go and Google mobile.