Three years ago, a GPS, also called a personal navigation device, was the most sought-after gadget. Popularized by Garmin, device sales shot up as we discovered the magic it could perform: figuring out where we were and telling us how to get where we wanted to go.

But sales slowed dramatically as more cars offered built-in navigation and Android smartphones added navigation. The smartphone offered big advantages: It was free, and it was always connected online so you could use Google to search for the name of the destination, eliminating the pain of entering an address letter by letter. But Garmin has persisted with new models that add connectivity, better performance and bigger displays.

Garmin’s latest top-of-the-line offering is the 3590 LMT (Lifetime Maps and Traffic), part of its Prestige line of 2012 nüvis. It contains the best of all of Garmin's features in a thinner form factor with a 5-inch display, new Guidance 3.0 navigation software, lifetime traffic data and online searching. (Lifetime maps means you are entitled to four upgrades per year. You can also purchase maps for other regions — for example, you can buy maps for Europe for $100.)

The Garmin looks a lot like a large smartphone with its 480 x 800, 5-inch touch display. It uses the same touch technology found on phones and tablets, which is much improved over the older resistive touch screens. It costs $400 at garmin.com.

The new user interface looks similar to that on earlier models, but numerous new features have been added, including quicker searches and better guidance leading through highway exits and intersections. While many models now display lane markings and traffic signs for the exits and junctions, this product displays photo-realistic images around these junctions and exits, using a database of 60,000 locations.

Traffic information is provided by an add-on radio receiver module, a thumb-drive-sized bulge that’s part of the power cord. So while the unit is thin, it will only provide traffic when plugged into your car’s 9-volt receptacle. The unit also comes with a suction cup window mount and charging cable.

In my week of testing, everything worked reasonably well. It acquired satellites quickly, except when I flew home from another city, when it needed a couple of minutes to access the local area. The display was bright and easy to read, except when bright light reflected off the screen. Maps were clear, much as on previous models. Controls to end navigation and turn off the audio are easy to access right on the display.

But even though it used a high-resolution display, the maps show limited details, similar to lower resolution personal navigation devices. At most magnifications, just a few street names were shown using black letters on white background patches. It has none of the fine details you’ll find on Google Maps. That’s OK when using it in a car to navigate, but less so when you carry the device outside of the car.

Traffic information, when it was available, was useful and displayed on the maps as well as in a list view of trouble traffic spots on major highways. The traffic service is free of any additional costs and uses data from a variety of sources, including other nüvi owners, historical traffic data and information generated by cellphones. In my use, I didn’t see traffic data on side streets, mostly just on highways, and on several occasions the data was inaccurate.

I found the nüvi to be much more convenient to use when driving long distances than using a smartphone, particularly with its 5-inch display. Its turn-by-turn directions and spoken street names were clearer, and its built-in mounting system let me permanently attach it to my car window. Also, navigation on some smartphones is suspended when the phone is in use.

The 3590 has its own built-in apps, including a Bluetooth speaker, trip planner, picture viewer, world clock, calculator, alarm clock, language guide and conversion tool. But most of these were fairly basic and not a reason in themselves to buy the device. The unit can also be used in portrait mode, convenient for mounting next to your rear view mirror or edge of the windshield without protruding into your field of vision. It also has voice recognition, which I did not try.

The unit comes with maps for North America. Updates and maps for other regions are downloaded using a serial cable through your computer.

While I’ve not reviewed them, Garmin makes many other models starting at $109. In fact, there are so many models that it’s confusing to figure out the differences. It seems there’s a different model name for even minor differences. You can get a model with nearly all the features of the 3590 for $100 to $150 less that sacrifices the lifetime features, voice recognition and display resolution. You’ll also find last year's models at Costco and other stores, some with model numbers not found on Garmin’s site.

The 3590 and its siblings with a 5-inch display are excellent in-car solutions for those without a built-in GPS. It’s also a huge benefit for those traveling in unfamiliar countries and is less expensive than the exorbitant charges that the rental car companies charge to rent their GPS systems. And unlike the navigation built into smartphones, you don’t pay for cell data. Yes, there still is need for stand-alone personal navigation devices, particularly with some of the recent improvements.

Baker is the author of "From Concept to Consumer" published by Financial Times Press and available at Barnes & Noble, Amazon and other booksellers. He has developed and marketed consumer and computer products for Polaroid, Apple, Seiko and others; holds 30 patents; and is an Ernst & Young Entrepreneur of the Year. Baker can be heard on KOGO AM the first Sunday of each month. Send comments to phil.baker@sddt.com. Comments may be published as Letters to the Editor. Baker's blog is blog.philipgbaker.com, and his website is philipgbaker.com.

City of San Diego and AT&T challenge developers to create the best app

In January 2012, the city of San Diego and AT&T challenged software developers to create apps that use city and partner data to enhance services and quality of life for San Diegans. Local app developers have been busy at work the last three months submitting ideas and building out mobile apps that will run on the Web, desktop computers, tablets or smartphones.

A panel of distinguished judges from the tech industry and venture capital and partner institutions will select winners, and the general public has been voting to identify two “Popular Choice” winners this month, with the deadline approaching on Wednesday.

Winners, to be announced on June 28, will receive $50,000 in cash prizes as well as promotional exposure. Among those submitted include apps that identify roadway repair needs and provide real-time transportation information, crime information and disaster preparedness.

For more information or to vote for your favorite app by Wednesday, visit sdappschallenge.com.