Car GPS system?

[Stana Claus]

Ever since my son turned 16 and got his driver's license and a job, he's not been able to go fishing with me nearly as often. As a result, I've lost my primary navigator. Trying to drive and follow the DeLorme atlas to find the turnoff for a new stream I'm looking for is a real PITA, not to mention hazardous for those around me. Do any of you folks know of a car GPS system that will let you put in your destination or a POI using latitude & longitude coordinates? I have an older model Magellan Roadmate 1412 car GPS, but it wants either a street address, intersection, or something from the built-in POI database as a destination, and that's just not that helpful.

I would like to be able to use Google Earth or various and sundry maps to find the coordinates for a given trailhead or stream crossing, plug that into my car GPS and let it talk me through getting there. Does such a thing exist? Anybody have one?