Garmin's G-12 Map Mapping GPS Receiver with UPLOADABLE MapSource CDRom Maps
Review by Joe Mehaffey and Jack Yeazel
Revised Oct 9, 1999 (Added MapSource 3 information)
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Many people have wanted a Garmin G-III PLUS but have not liked the case style of the G-III products because they do not fit smoothly in a pocket.  Others have wanted an audio alarm which the G-III products do not have.   The new  G-12 MAP receiver takes care of these problems and adds many new features as compared to the G-12XL's features set.

The G-12MAP is essentially a G-III PLUS mapping GPS receiver packaged in the G-12XL style case.  It has all the features of the G-III PLUS  (except rotatable screen display) and in addition has an audio alarm buzzer.   The G-12MAP expands Garmin's line of GPS receivers capable of uploading user selected maps from the Garmin MapSource CDROMs.  (Note:  Scanned maps cannot be uploaded nor can users edit maps uploaded to the G-12Map/G-III PLUS.)   With MapSource maps,  users can select local areas of interest (by approximate county size map modules) and upload detailed maps (essentially Tiger maps) into their G-III+ receiver.  The GPS will then provide a moving cursor on the moving map showing your position on the GPS map.   Garmin's MetroGuide maps CANNOT be used with the G12Map.

By using the "US Roads and Recreation" CD by MapSource, the user GPS storage area allows uploading of from 1 to 25 (max) counties into the G-12MAP.  Depending on area,  our experiments showed you could usually upload   6 to 12 counties (the boundaries of which are indicated as dashed lines on the GPS) depending on the road density in a particular area.  The counties do NOT need to be contiguous.   In the dense Atlanta Metropolitan area,  an area of about 7500 square miles of residential street level maps can be uploaded into the approximate 1.4 megabyte user memory, about 65% of the capacity of the Lowrance GM-100.  (Note:  The Lowrance GM-100 and the G-12MAP/G-III PLUS are "head on" competitors in the marketplace and we will make comparisons from time to time in this review.)

Garmin also has  a World Map CDROM providing limited road information for the world and also a TOPOgraphical Map version (for the USA only) which provides topo map features.   The "outside the USA map detail is substantially less than the USA road detail.  Garmin's  World Map and TOPO MAP CDROM products are also uploadable into the G-12MAP.    (Note:  This is because of the very high costs of acquiring accurate and highly detailed road maps outside of the USA.  Auslanders  should be working on this with your government representatives!).  However,  the detail on the new WORLD MAP CDROM is considerably better <everywhere we looked> as compared with the GM100 world maps.  The MapSource WORLD MAP also includes "some"  marine navaids whereas the GM100 world maps do not.    See comparisons of the Lowrance GM-100, G-III, and G-III+ (and G-12MAP) US and World Maps (HERE).  Note:  As of September 1999,  NO software other than Garmin's MapSource CDROM Maps can be uploaded into the G-12MAP/G-III Plus.

Look and Feel

One of the first thing you'll notice is that the maps are more 'readable' than the Lowrance MapCreate maps.  The major streets are heavy-lined instead of double-lined making them stand out more and have about 10% more street-vector resolution.  Highways and street names are designated more often too.  'Creeks' are two-dimensional gray-scale instead of thin lines.  However, this may eat up more memory than MapCreate does for the same 'creek'.  Lakes and rivers are gray-scale in both.

The G-12Map Receiver

The new G-12Map is basically a G-III PLUS receiver.  (Click HERE for product review) .   Unless noted otherwise,  all features of the G-12Map are the same as in the G-III PLUS all G-III/PLUS/G-12xl/cx accessories work with the G-12Map.  The G-12Map has been enhanced with additional memory and software (compared to the G-12XL) to permit the upload of vector maps from Garmin's new MapSource CDROM Map package.  All of the added memory in the G-12MAP is internal as opposed to a removable cartridge.  Unlike the G-III PLUS,  the G-12Map is equipped with an  audio alarm.  The G-12Map comes with a DATA (only) cable, wrist strap,  manual,  batteries (but no carrying case) and is ready to go right out of the box.  The G-12Map has an internal antenna like the G-12xl as opposed to the external rotatable antenna of the G-III PLUS.

There are a number of new menus in the G-12Map to support the new mapping features and  zoom in/out  buttons for the map screen.   With the G-12Map  you can do the usual route/waypoint/track  management,  (including TrackBack and MARK) but none of the automated route functions of the StreetPilot are available in the G-12Map.    SA5 or SA6 can be used to upload routes into the G-12Map  as in other Garmin products.  G7TO 3.04.04 (or higher) can be used to up/download waypoints,  routes,  tracks and screen photographs just as with the G-III PLUS.

Detailed differences between the G-12Map and the G-III PLUS

The case of the G-12Map is like the G-12XL case and  with a MCX connector for the external amplified antenna.  Although the G-12Map takes four size AA batteries, the antenna voltage output is in the range of 2.5 volts, and so you cannot  use the unit with the standard (nominal 5 volts) amplified external antennas.  Instead, you must use either the Garmin GA-27C or the Tri-M 2.5volt antennas (which are also compatible with nominal 5 volt GPS receivers) with the G-12Map (and with the eMap).

The G12Map has an audible alarm beeper. There are three settings:      None, "Message Only", and "Key & Message" (sounds every time you  press a key) . There is no option to allow sounding the beeper on selected messages only (for example only on approaching a destination).   Even in the "Message Only" mode, the beeper still seems to sound more often than I like.

Case:   The case is identical to the 12 CX. The buttons are labeled QUIT,  (Light), GOTO, IN, OUT, PAGE,  MENU, and ENTER/MARK.

Screen:   Identical to the III+ (100x160 4 level gray).   10 levels of  backlighting are supported.  LANDSCAPE display mode is NOT supported on the G-12MAP.

Other features in the G-12Map

The G-12Map has new features that permit you to locate the nearest  cities and expressway exits.  This feature does not recognize major state freeways (such as Georgia 400)  as expressways and only recognizes Interstate Highway exits with the "nearest exit feature".   Airports and some service facilities are also marked on the  new base maps.  The receiver displays 56 waypoint icons as compared to the G-III's 48.

Garmin has removed the firmware revision level from the initial screen so customers will not have an easy way to determine which software revision level is in a unit at time of purchase.  (You can get it by holding ENTER while powering up.)    However,  software updates should be available on their website as usual for recent equipment.  The software revision level of the G-12MAP does appear on the information window that appears on MapSource when maps are being uploaded to the GPS.  The unit used for review had 2.01 with background (Land Data)  map version 1.0.

Battery life in the NORMAL mode on the G-12Map  is somewhat more than 20 hours  of continuous operation on five different sets of Sony AA alkaline batteries.  A "power save" mode that provides a fix every five seconds as opposed to once per second is supposed to increase battery life  "up to 36 hours" according to Garmin.  (We got 29 hours continuous running in battery save mode.)  A new feature (common to the G-III PLUS)  in the trip computer allows you to select TOTAL TIME or TIME MOVING  TIME for speed calculations.  It is possible to turn OFF the MapSource maps and just use the base map if desired.

Features in the G-III PLUS but NOT in the G-12Map

The G-12Map screen cannot be rotated horizontal and vertical as can the G-III PLUS.  The G-III PLUS has a removable (quadrifilar) external antenna with a BNC connector.

MapSource CDROM Electronic Maps  ( Now updated to version 3)

The  Garmin MapSource maps are high quality electronic maps and the system is easy to understand and use.  The USA  maps  ("Roads and Recreation") are of the same general  quality as Delorme SA5 maps but lack the "tourist interest" and highway detail provided in SA6.   MapSource road accuracy is judged "good"  by Jack and Joe.   MapSource maps are more up to date and contain slightly more detailed water features as compared to the Lowrance CityStreets Maps provided with the GM-100 family of GPS. (Click HERE for product review)  For a side-by-side comparison of the features of the G-III+ and GM-100 (Click HERE).

MapSource was designed to provide uploadable maps to the G-12Map/G-III+ and other Garmin GPS products.  In addition,  starting with version 3.0,  MapSource systems provide the ability to:  a) upload/download routes, tracks,  and waypoints to the GPS,  b) allow the user to manually generate a route and upload,  c) print maps,   d) manually input waypoints and routes onto the map for later upload,  e) allows waypoint editing both on the map and in text form.  In addition,  there are many convenience improvements and bug fixes.  Note:  MapSource 3.0 is a free update from the Garmin website for purchasers of ANY MapSource product.  In addition,  prior purchasers of PCX5 can receive an $80 discount on the purchase of any MapSource product since PCX5 is being discontinued as all PCX5 functions are now included in MapSource 3.0.

 It is still necessary to use an accessory package such as SA6 for automatic route generation and route tracking on your PC.    NOTE:  The G-12Map *is not* a StreetPilot and it does not have the routing  or "address finding" capability of the StreetPilot.  Nor does it have the capability to 'LOCK' the GPS tracking icon to the roadway as does SP.   So far there is no program like OziExplorer/MapCreate that provides editing the MapSource files.  Waypoint+ and G7TO have the same capabilities with the G-12Map,  G-III+ as with the G-III.  Richard Bollar has collected a fine group of G-III and G-III PLUS comparative screen shots.  CLICK HERE to see how the G-III and G-12Map/G-III PLUS   with MapSource uploaded maps compare in street detail in Richard's area.

Water Data and Nautical Navigational Aids

Lowrance has historically included the most detailed water data in any available low-cost GPS receiver.  But a review of the maps comparing the G-12MAP/G-III+ with the GM100 reveals that the Garmin MapSelect has a noticeably higher shoreline vector resolution than the Lowrance MapCreate.  This is now a reversal of the situation with the GM100 and the G-III.

                                                                (Screen shots via G7ToWin)
                                 Maps of Lake Lanier Shoreline                          Map of a Small Lake Near Joe's House

   GM100                  G-III+                      GM100                G-III+                     GM100               G-III+

However when it comes to Nautical Nav Aids, MapSource has considerably fewer than MapCreate and no obstruction markers..

Comparing Nautical Nav Aids of MapCreate and MapSource near Savannah, GA
 (Placing the cursor over the nav aid reveals additional information.)
         GM-100             G-12MAP                  GM-100            G-12MAP                    GM-100             G-12MAP

Still,  nautical navigational aids in the G-12MAP/G-III+ are quite extensive.  Garmin informs us that the USA CD has all the US Nautical navigation aids of day beacons, radiobeacons, RACONS, fog signals, lights,  buoys and other navaids for the 50 states.  (This is basically the same marine nav-aids found in the  GPS 48) It also contains inland  nav-aids, including boat ramps, marinas, campgrounds, ranger stations, mile markers, first aid stations, etc. (same information as in Garmin's  Inland G-charts).  (See comparison of inland mile marker, state park and marina icons on Chickamauga Lake near Chattanooga, Tennessee (HERE).

The WorldMap CD will have  nautical navaids for the entire world.

Fonts and Rectangles

The font size of most all the names in the G-12MAP maps can be controlled INCLUDING the street-name font.    The greater number of street names and larger font of the Garmin sometimes obscures the road at certain zoom levels.  By selecting 500' instead of Auto in the Map Setup> Line> Street Label and/or reducing the street name font size in map setup, this clutter can be reduced or eliminated.

A distraction (to Jack) are the boxes drawn around each county loaded in the GPS.   (See below.)  Their purpose is to indicate what areas have been loaded in the GPS  The boxes can't be turned off when using the G-III+ for navigating.   (Joe did not have any problem with the boxes, so the question of "will the boxes will be a distraction?"  is quite subjective.)  See below left.  Also,  the extensive "crosshatch" which was present at the intersection of the basemap and the overlaid MapSource detailed maps has been substantially reduced in MapSource version 3.0.  At any time the crosshatch is bothersome (and overlays the base map area you are trying to use),  you can turn off the MapSource maps in map setup temporarily.

 The G-12MAP (and G-III+)  has enhanced BASE MAPS compared with the G-III.  Included are more major city streets,  and airport locations.  Many Interstate Highway exit services and facilities are included in G-III base maps.

"Boxes" around counties uploaded to the GPS    Streets and Exit Information  on G-12MAP/G-III+

                         G-III+                             G-III                     G-III+                  G-III                G-III+

Features of MapSource include:

1)  Detailed residential street level maps of the entire USA including Alaska and Hawaii.
2)  The user interface is easy to use.
3)  The system operates on a Windows 95,  98, or NT environment.
4)  Pentium Processor, 16 megs RAM, CDROM drive, mouse, 256 color display, 10 megs hard drive space required.
5)  Upload of a selected group of maps (called a "map set") runs at up to 115kbaud.
6)  You can preselect any number of map sets and later select a map set and upload it.
7)  It is easy to zoom in/out and slide the map around or use "hand" to view map details.
8)  A "find city" feature is provided to permit quick location of a particular map area.
9)  A  Garmin (or 3rd party) PC to GPS interface cable is required to upload  mapsource files to the G-12MAP.

MapSource cannot:
1)  Generate an address-to-address route automatically.
2)  Track your current position on your laptop computer.
3) Operate on a MAC computer without a PC emulator.


The Garmin G-12MAP (about $340, includes DATA CABLE) and the accessory MapSource CDROM Map system (about $100) constitute a quality and capable road navigation accessory.  (Check latest prices HERE.)

Comments?  Questions? Additions? Errors?
Contact:  Joe Mehaffey or Jack Yeazel

Thanks to Michael Polymenikos for his G-12MAP experiences which are incorporated into this review.