One of the worst things about car navigation systems is that you have to constantly glance away to either a smartphone or an infotainment display to see the map.
This is not only annoying, it's dangerous.
Heads-up displays help solve this problem by putting basic navigation information right in front of you on the windshield so you never have to take your eyes off the road.
My favorite experience with a heads-up display has been in Audi's 2017 Q7. In this vehicle, the display is in full color and it shows you not only upcoming turns, but also the speed limit and how fast you are driving.