15. Configuring Avoidances

Figure 73: Avoidances

The nüvi 205 is set to avoid U-Turns and Traffic by default. You can adjust the avoidances via the Avoidances menu, shown above (Tools > Settings > Navigation > Avoidances).

16. GPS Sensitivity

Figure 74: Garmin nüvi 200 vs 205, GPS Signal Strength

The nüvi 205 is equipped with a high performance GPS receiver. Throughout my testing, the nüvi 205 had no trouble quickly acquiring my position, and was able to maintain reception, even when driving in challenging conditions (i.e. in New York City behind tall buildings).

The nüvi 205 and nüvi 200 appeared to be about the same in terms of GPS sensitivity, although the HotFix-equipped 205 acquired it's initial position much faster than the 200. The nüvi 205 typically acquired its position and was ready to navigate within a few seconds of powering on the device. The non-HotFix equipped nüvi 200 took considerably longer to catch-up.

Figure 75: Garmin nüvi 765T vs 660 vs 205

The nüvi 205's "high performance" GPS receiver worked well, and is an upgrade over the previous chipset used in the nüvi 200. However, when compared to the more expensive nüvi 765T, or the discontinued nüvi 660, the difference in performance was clear.

To test GPS sensitivity, I placed all three units indoors. The nüvi 765T had the strongest signal, registering 22 foot accuracy (again, this is indoors. Outdoor performance was even stronger). The older nüvi 660 (which uses SiRF's StarIII chipset) registered 38 foot accuracy. The nüvi 205 was roughly three times less sensitive than the nüvi 765, registering 77 foot accuracy.

17. Routing Engine Performance

All the bells and whistles aside, what really matters on any GPS is its ability to intelligently get you from point A to B.

The most common complaint I hear about any given GPS system is that "it took me on a wild goose chase", followed closely by: "that was definitely not the best way to go."

How well or poorly a GPS is able to route you to your destination is a function of two critical components: the routing engine, and the quality of the maps installed on the device. The routing engine is the internal logic the GPS uses to figure out the best route to take. Many people falsely assume that simply having the same maps installed on two different GPS devices will result in the same routing choices. Not so, as there is a great deal of math, personal preferences, and economics going on behind the scenes when your GPS calculates the "best" route.

Not surprisingly, routing engine performance is one of the most complex aspects of any GPS system, and is generally not well understood by consumers. In truth, routing quality is probably the single most important aspect of any turn-by-turn GPS device, and should be a determining factor when purchasing a GPS.

The two largest mapping data providers are NAVTEQ and Tele Atlas . NAVTEQ used to have a slight advantage in mapping quality in North America. However, Tele Atlas has improved its US database in recent years, and both companies are now roughly equal in quality. The mapping provider shouldn't be a determining factor in routing quality, as both NAVTEQ and Tele Atlas are capable of providing excellent maps to GPS manufacturers. That said, it's important to understand that both NAVTEQ and Tele Atlas sell many different levels of maps, ranging from inexpensive data sets that only contain basic information to more expensive offerings that contain much more detailed information.

For example, is a road closed to commercial traffic? Does a given road close at night? Are there weight restrictions on a certain highway. All of these are examples of additional information available to GPS manufacturers, at a cost, to factor into the GPS' routing logic. The number of attributes used varies depending on how much money the manufacturer is willing to spend on their mapping data. For example, a full NAVTEQ map database that includes all available attributes can cost the manufacturer twice as much as a basic set of attributes.

Even when two different devices are provided identical map sets, each manufacturer makes numerous decisions that impact routing. For example, statistically speaking, making left turns is more dangerous than right turns. Some devices will favor right turns over left turns, even at the expense of additional travel time.

When testing routing logic, I'm looking for routing logic that can make intelligent decisions about which roads to take. I'm not looking exclusively for the shortest distance, as often a slightly longer distance will be much less trafficked and result in a shorter overall drive time. I'm also looking to see if a device is sophisticated enough to understand that at 5pm on Friday, many highways are parking lots, and surface roads should be favored. Also important is the GPS's ability to gracefully handle missed turns, and quickly re-route.

Test #1: Actual Road Test

To test the nüvi 205's routing engine, I drove from New York to Boston and back.

I also brought a Magellan RoadMate 1400 along, as well as a TomTom XL 330 S, and compared the routing decisions, ETA accuracy, traffic alerts, missed turn re-routing, and GPS signal reception quality on all units.

The nüvi 205 performed well in real-world driving tests. GPS signal performance was solid, and the 205 had no problem maintaining a strong signal when driving behind tall buildings or through short tunnels.

The nüvi 205 appeared to be better at handling missed turns than either the TomTom or the Magellan. When I would miss a turn, the Garmin nüvi would quickly realize the turn had been missed, and plot a new course based on my current heading. The TomTom and Magellan would also realized I had missed a turn, and announced that they were "re-calculating", but they favored lengthy U-turns or backtracking instead of truly re-calculating based on my new heading.

For example, when I missed a highway exit on I-95, the nüvi 205 quickly re-calculated, allowing me to continue on towards my destination, and found another route that was only 2 minutes longer. By contrast, both the Magellan and the TomTom wanted me to exit at the next opportunity, get back on the highway going in the opposite direction, exit again, get back on the highway, and take the originally planned exit. In other words, a 10 minute u-turn.

Out of the box, the nüvi had the most accurate ETA times. Even on a 300+ mile trip, my actual arrival time was within 10 minutes of the nüvi's original estimate. Magellan's RoadMate was also very good at predicting the ETA. TomTom's ETA fluctuated wildly while driving; if I drove 80 MPH for even 2 minutes, the TomTom would adjust the ETA drastically and shorten the estimated drive time. If I sat in slow traffic for a minute or two, TomTom's estimate would jump way up.

Garmin's nüvi learns driving behavior as you use it, and, over time, its ETA predictions become more accurate. TomTom's XL 330 S and Magellan's RoadMate do not have the capacity to learn driving behavior over time (note that TomTom's more expensive GO models have a feature called IQ routes, that allows the GPS to base routes off of historical driving patterns).

From a pure routing perspective, the Magellan and Garmin were roughly equal, though I tended to prefer Garmin's map screen. TomTom's XL 330 S had an uncanny knack for routing me straight into traffic jams, and seemed to have no awareness that I-95 would likely be slow moving on a Friday during rush hour.

All three units were competent, and successfully guided me to my destination. However, I found Garmin's nüvi 205 the most comforting to use, and the most consistent performer in the group.

Test #2: Simulated Routes

I also performed a series of bench-tests, entering three different trips of varying distance in three different regions of the United States, and comparing the nüvi's results to the Magellan RoadMate, and TomTom XL 330 S. All three test units had the latest available maps installed, and the most current firmware as of this writing.

Our first test took us along the Northeast, starting in Southbury, CT and ending in New York City:

Magellan's RoadMate 1400 and Garmin's nüvi 205 choose essentially identical routes. The Garmin nüvi is slightly more aggressive in its estimated drive time, and gives more verbose instructions, but both GPS units do a good job routing. Both announce which side of the street our destination will be on, and both ensure that we arrive with the destination on our right side.

TomTom's XL 330 S has us arriving with the destination address on the opposite (left) side of the street. We would then either have to make an illegal U-turn or go around the block to arrive at 135 Central Park West on our right. TomTom is also the only GPS that reports distances in yards instead of feet, which I found annoying after a while.

Yahoo! Maps (not shown in the table above) chooses a route identical to the RoadMate and Garmin nüvi, but estimates the trip will take 3 minutes longer than Garmin estimates (1 hour 22 minutes). Google Maps also chooses the same route as the Garmin nüvi and Magellan Maestro.

Winner of Test #1: It's a tie between the Magellan RoadMate 1400 and Garmin nüvi 205.

The first test was approximately 80 miles in length and took us from Connecticut to New York City.

For the second test, I started out at Fry's Electronics in San Jose, California and entered a destination address at 300 Grove Street in San Francisco (about 46 miles in distance):

Again the Magellan Maestro and Garmin nüvi choose virtually identical routes, and the TomTom XL 300 S chooses the least efficient route. While Magellan and Garmin both route us along the 101 highway from San Jose to San Francisco, TomTom's XL 330 S instead routes us along highway 880 North to 80 West -- an odd choice that adds around 4 miles (~6 minutes) to the journey, assuming there's no traffic 880 (which there usually is). Even worse, TomTom again has us arriving on the wrong side of the street, with our destination address on the left.

Both the Magellan RoadMate and the Garmin nüvi arrive with our destination address on the right side of the street, and both units announce what side of the street our destination is on.

Winner of Test #2: It's a tie between the RoadMate 1400 and nüvi 205.

For the third test, I chose a short, 3-mile trip from Beacon Street in Boston to Cambridge, Massachusetts:

Magellan's RoadMate just slightly edged out Garmin's nüvi 205 in this test, and TomTom's XL 330 S again comes in third.

TomTom's XL 330 S unit performed least well in all three routing engine bench tests, producing the longest routes in all three tests, and putting us on the wrong side of the street at our destination address.

I've received many questions asking why it's important to arrive on the right side of the street. In more rural areas, it likely won't make much difference if you arrive with your destination on the right or left. However, when driving in cities along wide avenues, such as in New York City, it's very important to arrive on the same side of the street as your destination. Otherwise you'll need to make an illegal U-turn or drive around the block.

Regarding the estimated drive times, some readers have commented that these tests unfairly penalize TomTom for more conservatively estimating the drive time, and reward Garmin for unrealistically aggressive (short) drive times. I disagree with these assertions, as I have actually driven many routes with all three devices connected and compared the routing choices made by each.