I have a Garmin Edge which is really a bicycle computer, but it works very well on the dash of my Van.  Has software to download to your laptop, can interface with Google Earth for track historys, etc etc.  Gives all kinds of real time data right on an LCD screen..Elevation, % grade, direction, track map, etc etc etc.  It'll run 8 hours on a battery charge(re-charges while downloading to a lap top or if running off a 12v power point adaptor)  You can carry it in your pocket, put it on a bike or a moto, whatever..Pretty cool dealie..

  Amazingly accurate...When it's on the bike, I use an 'auto stop' mode so that the batteries last.  You can take the bike and wave it around without moving your feet...the GPS KNOWS..
  Don Hanson