I use the Nav in my 2008 X5 & we have a Garmin that we use in rentals.

Both use Navtec base maps. If you are using the same version (annual updates for both) there is no difference in the map.

Features between the two systems are different as is the interface software, Both will get you to the correct location (usually) however if the base map is incorrect neither will.

Base maps are updated annually. Our US road network has thousands of changes over 12 months. So until someone comes up with a way to correct base maps dynamically as construction changes occur this is not going to change.

Hope this helps.

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2008 4.8i Mineral Green Metallic Sports Package, Technology Package, Cold Weather Package, Rear Climate Package, Premium Package, Premium Sound with iPod adaptor & Sirius Radio, Auto Tailgate, Head up display