The race is on with three sat-nav contenders for the iPhone.

Sygic's Mobile Maps 2009 met to mixed reviews when it was released in June, partly because it lacked polish and partly because it became obvious that the iPhone really needs to be in a cradle to get a good GPS lock for satellite navigation. Navigon joined the party in July and now TomTom has released its iPhone app - before the TomTom iPhone cradle goes on sale. Launching without the cradle is certainly a risk in terms of GPS performance, but to wait would risk losing early adopters to Sygic and Navigon.

I put the three sat-nav apps to the test using a makeshift windshield mount in landscape mode and the results were much better than with the phone sitting in the coffee cup holder or being held by the passenger. From my tests, the iPhone's GPS accuracy drops considerably when someone is holding it, to the point where it falls a street or two behind your location.

When it comes to pricing, you're looking at $69.99 for Navigon, $79.99 for Sygic and $99.99 for TomTom. It's cheap when you consider the price of a dedicated sat-nav, although you need to allow for the extra cost of a decent iPhone car cradle or windshield mount. Each app has its strengths and weaknesses but, when it comes to onroad usability, so far I'm leaning towards TomTom. For example when Navigon approaches a roundabout the voice tells you to take the "second exit", while TomTom and Sygic say helpful things like "cross the roundabout" or "turn left" and then tell you the number of the exit.

Sygic forces to you specify Australia or New Zealand each time you enter an address, which quickly becomes tiresome. Neither Sygic nor Navigon take into account your current location or history when choosing a destination, so for example when you press A to type a suburb name you're offered Adelaide first even if it's a thousand miles away. If a nearby suburb starts with A, TomTom tenders to offer it up before Adelaide. Only TomTom and Navigon are integrated with the iPhone's address book, while only TomTom and Sygic automatically show you a list of recent suburbs when you're entering a destination. When you're in landscape mode Sygic lets you see the top three options from a list, while TomTom and Navigon only let you see one. Switch to portrait mode and Sygic reveals 7 options, with 3 from TomTom and Navigon.

I really like the fact that TomTom automatically asks me if I want to avoid tolls if they are included in the route, rather than expecting me to specify this in the settings or change the route profile.

When it comes to the onscreen display, I'd also learn towards TomTom. I like the fact Sygic displays the current speed limit, but I think it tries to cram a bit too much onto the map. The amount of clutter can make it difficult to see the name of the street you want to turn into, especially when you're in night mode. On the other hand, Navigon's display is a little spartan although it offers the clearest diagrams of what an upcoming intersection looks like - which is important considering its voice gives you less information than the others when you're approaching a roundabout.

The biggest shortcoming with the Sygic app is that, if a call comes in, after you hang up you have to press the button to agree to the fact that you won't press buttons while you're driving. This is a stupid bug which Sygic has promised to address in the next update, along with introducing address book integration and text-to-speech for reading street names aloud. I reckon text-to-speech is an invaluable feature in a sat-nav device - so I'd be tempted to wait and see if it's any good before I laid down any money.

All three applications are likely to get updates in the near future as the providers add polish and address bugs. If Sygic can offer text to speech then you can be sure the others are working on it as well
[UPDATE: Navigon has confirmed its next update will include text-to-speech]. As such, I'd recommend holding off for a while to see what they'll come up with, but at this stage I reckon TomTom is the one to watch.

[ Via Digihub ]