Hello, just got a 2013 Grand Cherokee Overland editiion "used" 7K milesl I live in Texas in DFW area. One of my uses for this vehicle will be to tow a Casita Travel Trailer. I have installed the brake controller and checked everything out. It came with the factory towing package. This is both a very useful and comfortable vehicle. I am still on the learning curve with this thing. Question: To get the Nav to display the vehicle speed and road info do I need the Sirius Traffic?