True story (I swear I didn't make this up): I was driving down Memorial Avenue testing out TomToms's 930 GPS system the other day when I saw a young man in a car in the lane next to me hunched over a map pressed up against the steering wheel. I felt like winding down my window and shouting: "It would be much easier with a window-mounted GPS."

The Go 930 ($899) is TomTom's top-of-the-line GPS device and it comes pre-installed with 45 maps covering New Zealand, Australia, Europe and the United States. The 930 features a 4.3-inch touch screen as well as an integrated FM tuner, Bluetooth connectivity and a dinky little remote control.

The screen is bright and clear, and running across the bottom is all the information you need while driving: distance to your destination, how far until the next turn, and even your current speed and the prescribed speed limit, all clear and easy to read.

If you want voice-activated instructions you can choose from four voices - two male, two female - and the voices are informative without being obtrusive as the voice modes on GPS units have been in the past. Testing out the unit on a variety of routes, from short commutes to trips to Lyttelton and Kaiapoi, the 930 did an excellent job of plotting our course and keeping us on track.

I loved how quickly it was able to recalculate the route on-the-fly despite several attempts to try and fool it by taking the wrong turn or another road. Not once was I able to trick it - and not once did I receive a grating "Please make a U-turn" like the last GPS unit I used while holidaying in Australia two years ago.

I was also impressed that the unit performed flawlessly during a drive through the Lyttelton tunnel - I was expecting the signal to drop as soon as I went under the Port Hills but, no, the 930 kept ticking along. I used to think that a GPS device wasn't necessary in a country the size of New Zealand.

But after having one for a few weeks I've decided a GPS is great no matter what size the country. In fact, it's also a marriage saver: you can get to your destination safe and sound with no arguments. That's a big thumbs up in my book right there.