The GPSMAP 276C is is a new Garmin model due April 04. See below.
I have a 176c and it is not much use on land in the car.
It will show you where you are on the chartmap, but it does not navigate road routes or give you directions as say the tom-tom software on a handheld PDA does.
The GPSMAP 276C is an all-in-one, versatile, colour chartplotter and automobile navigator - perfect for land or water. This portable GPS navigator features a 256-colour TFT display that's easy to read in bright sun along with a built-in basemap and auto routing to provide you with turn-by-turn directions to the marina for a day of boating.
On water, the GPSMAP 276C is a dependable, colour chartplotter with a built-in Autoroute basemap enhanced by Garmin's marine cartography. It accepts pre-programmed or user programmed data cards with MapSource BlueChart for offshore detail or Recreational Lakes with Fishing Hot Spots for detail of inland lakes.
In addition, the GPSMAP 276C supports external NMEA sources for water depth, water temperature, and water speed through two serial interfaces. The unit also features a new Course Deviation Indicator (CDI) - an advanced navigation tool commonly found on aircraft, but equally practical in the marine environment. The CDI quickly indicates if a boat has veered off course.
On land, the GPSMAP 276Cís European Autoroute basemap features major roads and motorways. With an optional automotive kit that includes MapSource City Select software, data card, friction mount, and 12-volt power adapter with speaker, drivers can receive voice-prompted turn-by-turn directions to addresses and points of interest throughout Europe.
For map transfer or software updates, the GPSMAP 276C features a fast USB-PC interface. The unit is also powered by a rechargeable lithium-ion battery pack, or a standard 110-volt AC plug