Factory-installed in-dash GPS systems increase the depreciation of cars, according to James Clark of Automotive Lease Guide. It's not that they don't add value; they just don't add much.
"Clark's example: A high-end 2007 Acura TSX sedan should be worth 55% after three years without navigation, 53% with. The $2,000 navigation option winds up adding no more than $600 to the value of the 3-year-old car, he says."
We've said it before, after-market GPS trumps factory-installed navigation units. The cost is lower, they are easier and cheaper to update, you can move them to another car, you have more options to choose from, etc.