Edmunds Daily has published an article talking about a road test of four connected PNDs in the US: TomTom, Alpine, Insignia and TeleNav.
Using a cellular connection (or an FM signal as an info carrier in the case of the Alpine unit) these systems can also get real-time traffic info, weather reports, gas prices, movie times, flight info, news, stock quotes and more. And two of the units have a Google search function that can find anything, just as if you were sitting at a PC — and can then route you to it.
In fact, we found that Google search was a make-or-break factor and feature in our testing. While looking for an Apple Store, for example, the two Google-enabled units — Insignia and TomTom — found them without a problem, while the TeleNav unit did not. And while looking for a Trader’s Joe’s the TomTom unit found it but the Alpine unit didn’t.