Does the navigation system use the same antenna as the XM? Does it pass through the XM reciever in the trunk or is it a separate system? GPS L1 (civil use) is about 1.6 GHz and XM is at about 2.3 GHz, so it seems reasonable they could use the same equipment. I'm considering getting a hand held navigation unit for other purposes and thought I could put in a splitter to allow me to use it in the car. If someone knows the answer it would save me some research time.

 

No, XM is on the roof, GPS is under the back deck lid.