When I've had occasions to rent a car with built in nav., it always seem to get the directions wrong. My Garmin almost always gets them right.

Gps
 

GPS' are absolutely great. How did we survive trips with our wives giving us directions from a map?

Instead of paying the extra amount of upgrade on a car to get a navigation system, just go to Best Buy, WalMart, Sam's, etc and get a Magellan or Tom Tom for well under $200 - and most are now coming with FREE LIFETIME updates of maps as well as FREE TRAFFIC reports.

The GPS is easily taken between vehicles and I even like to use it in a game called "geocaching". My Tom Tom gives the exact coordinates of where you are standing down to the second. Try geocaching. It is quite a bit of fun to find the little caches.

Used to and still will when in our other vehicle without OnStar or I just might try my GPS navigator in my cell phone. Also, I don't know about other GPS's but OnStar only recalculates when you leave the planned route by accident, to get food, gas or whatever reason!

Trouble with a paper map is you need somebody be to reading it while you're driving

I have a navigation system in my car and I have a portable Garmin system that I purchased for use in rental cars when I travel. I think most of the comments here have covered the advantages of purchasing a portable system (lower cost, can be used in other vehicles, can be programmed by a passenger when the vehicle is moving, cheaper map updates, etc) fairly well.

However, there are also some advantages that favor a factory navigation system. First, factory navigation systems tend to have larger screens (7 or 8") that are easier to read. They are large enough to use in split screen modes (showing your next turn while showing where you currently are). Second, the system is always there when you need it (you can't forget to take it with you). Third, you don't have to be bothered with unplugging it and putting it away when you leave the vehicle and then setting it up when you return. (My son got lazy one night and left his Garmin on his dashboard and someone smashed his window to steal it.). Fourth, you can have the radio on without worrying that you won't hear the instructions for the next turn because most systems will lower your radio volume when giving navigation instructions. Fifth, portable systems like my Garmin often have suction cups which will start failing and cause your portable system to fall off the windshield, usually at the worst possible time. Finally, factory navigation systems are often packaged with rear backup cameras. I find the rear backup camera to be very useful, especially if your car has blind spots. A couple of manufacturers have started offering backup cameras without having to purchase a navigation system.

Is it worth the price to purchase a factory navigation system? I don't know if I would purchase it on my next car or not. However, I just thought someone should present the other side.

On star is great
 

On star for gm cars is great. There price for unlimited minutes has been greatly reduced and it is completely hands free as skyguy stated. Very safe. Also, it is like a personal attendant that you can not only use it for navigation but it will tell you were the nearest starbucks is or any other reasonable request. You are talking to another human being on the other end and they actually care about answering your question or making sure you are completely satisfied. This type of service is getting rarer each day. GM got this right.
:BigApplause:

You can say that again! There is another thing OnStar can do that no other GPS can and that's assist if your car is stolen. Read about it at the following web page and view the video available there! You just might be amazed! http://www.onstar.com/web/portal/securityexplore?tab=1