Just purchased a 2013 Venza with nav system and it came with SirriusXM trial for 3 months. I asked the dealer how to update the maps in the nav system and he said that it does it automatically thru Sirrius? My questions are, 1. Is this true? 2. If it is, do you always have to subscribe to Sirrius for updates? I am concerned that the two are tied together because I was not going to keep the Sirrius past the trial, so how would I get map updates? Any help would be appreciated.