Is it better to purchase a car with a built in navigation system, or to purchase a GPS unit, such as a Garmin instead?

Economically to have aftermarket. Built in systems are pricey options you will never get your money back on when selling and killed if they break down and also integrate other car functions(some run radio/climate control/other functions).

I like the portable units, they are cheaper (less than $500) and can be moved between vehicles. I have one semi-permanently installed in my car with velcro and a hard wired power supply, I can still unpluf it and take it with me.

There are advantages and disadvantages. The built in unit is expensive and cannot be moved to another car. The portables have a high theft rate because they are easy to remove. Thieves look for the suction cup marking on the windshield to see if there may be a portable GPS in the car.

I would go with the portable unit. Get a small one and you can carry it with you.

Portables are a better choice in my opinion. The built-ins are invariably a couple of generations behind the latest portables because of the lead time involved in automotive production. You can’t easily upgrade a built-in, and they cost at least twice as much as even some of the best portables. If you want to scrimp a little you can get a good portable for 1/4th the price of the optional built-in.

The built-in are nice and easy to use. Some have voice control, although you don’t really do much controlling if any when using one.

The portable ones means you can use it in many cars and most now will work when you are just walking around, great for cities you don’t know well.

“The built-in are nice and easy to use. Some have voice control, although you don’t really do much controlling if any when using one.”

My portable also has voice control, bluetooth phone connections, and all that stuff. To tell the truth the voice control is probably more trouble than it’s worth. I have a Maestro 4250, shown on this page (it seems to work pretty well):

I think a portable unit is a better option. Better yet is to get a cell phone that can also handle navigation. This way, although you pay a monthly fee (but you don’t have to buy a gps), you also get regularly updated map information without having to purchase the map upgrades for a dedicated gps each year. And, you can choose not to pay for a month that you don’t need it. I think built in units are becoming obsolete due to cost effective portable alternatives.

If you do get the Aftermarket GPS unit…then make sure you can EASILY remove it. There have been a rash of break-ins in the Boston area to steal them.