There are many websites dedicating to comparing products. You can always read the reviews for each product on websites such as amazon, or search for more specialized reviews on sites like CNET or eHow. Consumer Reports may be helpful as well.
Garmin has a website also you can go to also goto www.NexTag.com or www.squidoo.com/gps-comparison
Portable GPS units work anywhere, in any car or handheld. A factory installed GPS unit generally cannot be moved to another car.
Looking for car GPS compare information on the internet can be quite simple if you look at numerous GPS reviews. Most GPS devices are popular nowadays, so it isn't hard to locate reviews on them if you search for the exact device that you are trying to learn something about.
The Acura in-car GPS units were the first to get traffic information overlaid on their GPS displays, and still are the best.
The military has gps technology accurate to approximately 1 millimeter. conventional gps units (like the one in your car) are accurate to about 15 feet.
If you are shopping around for a GPS device, it is an excellent idea to conduct a car GPS comparison before you make a decision on a GPS device purchase. By performing a car GPS comparison, you can identify the key features in each GPS device and compare them against the other GPS devices. When you do this comparison, it is often easy to see which of the many GPS devices is best for you.
Compare current GPS prices with those from just a few years ago, and it's obvious that they have continued to plunge as more and more people recognize the benefit of being able to navigate accurately anywhere they go. GPS units that commanded over $300, as recently as three years ago, have been replaced by even more capable units that can be purchased for under $100. There also seems to be a trend in that direction of free data updates for these GPS units.
Best Buy sells several different types/sizes of GPS units. They sell portable as well as handheld units, which some people might refer to as pocket sized. http://www.bestbuy.com/site/Car-Audio-GPS/GPS-Navigation/abcat0301000.c?id=abcat0301000&searchterm=gps&searchresults=1
Some companies install GPS units in their vehicles.
You can view GPS videos to compare different GPS devices and different GPS brands on youtube.com. Just enter the different brands and devices that you would like to compare.
No, there isn't a monthly fee for Garmin GPS units. There many be additional charges for GPS upgrades though, aside from the initial cost.
I don't see a specific comparison site but sites like CNET and Amazon have many reviews of all sorts of GPS units, Magellan and otherwise. You could also check Magellan's website.