Built-in car navigation systems aren't much help if you end up taking your buddy's car instead of your own. Cobra Electronics' NavOne 3000 navigation system addresses this problem by letting you move it from one car to another. Unfortunately, although the device has some nice features, its clumsy design and slow operation prevent it from working as well as competing products do.

The $1299 NavOne isn't the first portable automobile Global Positioning System (GPS) unit I've seen, but it offers at least one feature that most others don't: You can beam addresses from your Pocket PC or Palm PDA via infrared directly to the unit.

The unit ships with a suction-cup bracket that is easy to attach to the inside of your windshield. Plug the unit's adapter into your car's cigarette lighter socket, and you're ready to roll. When you want to move the unit to another car, simply take the whole package with you.

The NavOne combines GPS capabilities with an internal hard drive that can hold maps and details on thousands of points of interest for the entire United States, along with limited coverage of Canada. You can download map updates on your PC and move them to the unit after linking it to your computer via USB 2.0.

Out on the road, I found the NavOne's 5.2-inch color LCD bright and easy to read. The NavOne's maps use the standard overhead, bird's-eye view. This works for turn-by-turn navigation, but it isn't as sophisticated as the 3D, forward-looking views offered by comparably priced portable automobile products like the Tom Tom Navigator and the Magellan Roadmate. Likewise, the location information was accurate, but the device seemed to refresh the data and to calculate routes at a slower pace than did comparably priced portable automobile models I've seen.

The NavOne uses a first-generation, button-style interface, so working though the menus takes a bit longer than it does on units that use touch-screens. Using the buttons to add addresses manually is arduous.

Another drawback of the NavOne is its size. Because it's bigger than a trade paperback (and significantly larger than competing models), it blocks more of your view when attached to your window. Its volume and brightness controls reside on the right edge of the box, so you have to make adjustments by feel while driving.

One the positive side, the unit includes an internal gyroscope that helps it continue to track your position if the satellite signal is temporarily lost.

In the end, however, the NavOne's shortcomings make it tough to recommend. Unless you're a PDA or Pocket PC addict determined to beam addresses to your GPS device, you're better off looking at competing products.