What Matters, What Doesn't

GPS prices are falling like rocks, and we found usable units starting well under $200 (the Mio C230). But even if you want top of the line, the Garmin Nuvi 760 ($750 list) is available at Amazon.com for just under our $600 price limit. About the only thing that didn't make the price cut were commercial-fleet-oriented products.

Each device category has dozens of features, but when you boil it down, half a dozen fundamentals separate the wheat from the chaff. In our survey, nearly everyone said the most useful feature is point-to-point navigation with maps with verbal-turning instructions. Conversely, more than 80% thought that Bluetooth wireless capacity for phone (using the GPS device as a hands-free phone adapter) was a waste.

Here are the fundamentals of GPS technology, and the features you won't want to skimp on.

WAAS. Be sure any unit you're considering is WAAS-enabled (Wide Area Augmentation System) to gain the most accuracy available within about 3 meters. Today's typical GPS receiver without WAAS enhancement is accurate to about 15 meters (50 feet)–maybe good enough to get your truck on the map, as long as you don't care whether you're on the road or in a ditch.

Connection Speed. It's important to consider how long it takes a unit to lock onto the satellites and fix your position. This can vary from a few seconds to several minutes, depending on conditions. Higher-end units use SiRF-Star III chipsets, which are faster, use less power, and are better in congested urban jungles than competing electronics. Better units also use what is termed a "high-sensitivity GPS receiver," typically working on 20 channels. Less-expensive units still use the old, standard 12-channel receiver. Avoid anything less than 12 channels.

Custom Points of Interest. GPS manufacturers make a big deal of how many canned points of interest they include. Like maps, this feature is only as good as the database supplied, which may or may not have the brands of hotels or gas stations that you frequent or even be up to date. For contractors and delivery people, it's much more important to be able to add and route efficiently to custom points of interest, "favorites," or waypoints, and have the unit alert you when you're getting close to one. This feature is what sets phone/GPS solutions and the soon-to-be-released Dash Express apart from the crowd.

Routing Engine and Map Service. For personal navigation devices, the routing engine is the programming inside the unit that determines whether you'll have clear sailing on up-to-date main roads, or crawl along on back streets with a stop sign at every block. There's no way to objectively test the routing engine, but like so many things, you'll know a lousy one when you're stuck with it.

There are two main mapping services that feed the routing engines: Navteq and Tele Atlas. Navteq is substantially more expensive for manufacturers to use but is better-focused on North America and more widely used. Google, Yahoo, MSN, and Mapquest maps all use Navteq for their North American maps. Tele Atlas is more European in focus. Generally speaking, you're more apt to find the bargain GPS units using Tele Atlas.

In terms of their ability to construct a good route, Garmin and Magellan products score the best with users, and my own experience bears this out. Garmin's routing engine is as good as it gets (which is why Avis chose Garmin as its GPS supplier for its North American rental fleet). Magellan is a very close second, with TomTom, the third most-popular GPS provider (and which uses Tele Atlas), bringing up the rear.

Maps. A GPS unit is only as good as the maps that are on it. Some low-end models have maps burned into their onboard memory, which can't be upgraded at all, or they ship with maps more than a year old. We found one unit, a NexStar Q3-01, with maps from 2000. It's best to stay with recent releases from brand names. I like units that will accept a standard SD card for updates vs. having to connect the unit to your PC.

Route Optimization. If you're doing a lot of job-to-job deliveries, you'll want your GPS unit to create the most efficient route between waypoints or favorites. Higher-end units from Magellan and Garmin do an acceptable job with route optimization, as do some of the phone/GPS solutions. The Dash Express (see page 31) promises exceptional features in this area, as it can be updated continuously via the Internet.

Text-to-Speech. Almost every personal travel assistant device, as well as most cell phone and PDA hybrids, will give you turn-by-turn directions, and most will speak them. But trust me, they're a lot easier to use if they also speak street names. This feature is usually called text-to-speech. What it means is instead of "In point-one miles, turn right," the unit will tell you, "In point-one miles, turn right on Hawthorne Street." I've used GPS units with and without text-to-speech, and I would not buy a unit without it. In fact, if you have a good text-to-speech engine, the size and quality of the screen itself is much less important.

Data Entry and Database Search. When you're trying to get your end-point programmed into a unit, the last thing you need is clumsy data entry. For instance, the Magellan Maestro 4250 wouldn't let us enter a place without the complete address, all the way down to the house number. If it couldn't find the exact street name in its database, the unit churned hopelessly until we manually rebooted it.

By contrast, all of the Garmin units took us to a generic town or city name if that's all we knew.

Windshield Mount. For GPS in your vehicle, how the unit mounts is more important than you might think. Garmin takes the prize for the best windshield mounting hardware we've seen.

Internal Speakers. Some units, like the egg-shaped Garmin StreetPilot series, have better internal speakers and are easier to hear in a noisy truck. In general, the smaller the unit, the worse the built-in audio output, although most of the thin and light units we tested from TomTom, Garmin, and Magellan were loud enough to be heard above road noise.

On-road and Off-road. Many of the personal travel assistants are portable enough to stick in your pocket, but once you're away from your vehicle, they're not of much use since their databases are all about what you find on the road. You won't find the compass, bread-crumb trail, geocaching, or other marine and hiking features that are typical of handheld GPS receivers.

That's too bad, because there are plenty of times you might be walking around in a strange city and need some guidance. If that's a concern, look for a unit with a pedestrian mode and off-road items in its database.

–Joe Stoddard is a contributing editor at Tools of the Trade, and a process and technology consultant to the building industry. Reach him by e-mail at joe.stoddard@yahoo.com.