Smart phone and any nav app of your liking. Waze in my case.
Now, seriously. Takes a year to make nav DVD and in a year it's already outdated. Waze or GM updates itself daily. Waze has direct feedback from folks that use it, police and hazard on the road included.
Why bother with crappy factory nav?
Well, does it tell you where police is? Or, hazard on the road? Or, potholes on the road? Or, on a fly updates for construction? Or, if there's car sitting on the shoulder? An accident that just happened few hundred feet ahead of you? Can YOU report back your feedback to help others? Does it allow you to modify existing maps to add, say, red light camera to them?
WAZE beats everything and is NOT data hog.