Tomtom Go 540 Live sat nav

Increasingly people are using their mobile phones to plan routes, the built-in connectivity making it possible to provide up-to-date searches and traffic information.

The Go 540 Live is a response to this. It has a built-in GSM module that provides a range of extra services over the Vodafone network. After the first three months, you’ll pay £8 a month for these.

The new traffic service works out how fast traffic is flowing on your route using data from other users and Vodafone’s own traffic monitoring system; sit in a traffic jam for a while, and you’ll either be re-routed or given a reassurance that you’re still on the fastest route ­ with an updated arrival time.

Cheapest local fuel prices are available too, along with speed camera updates, weather and buddy locations. An integrated Google search means you can even navigate to the nearest takeaway if the need arises.

A help menu lets you see your exact location with options to call, drive or walk to locations such as hospitals, police stations or pharmacists. All very useful, as too is the voice control, which needs no training. Tap the screen and say, "navigate to an address" and you can say where you want to go. It can also read out traffic reports for you. You can enable speed limit warnings, and lane guidance is clear and helpful.

But while route directions were clear, the Bluetooth hands-free functions were far too quiet, and some functions, such as reading text messages, didn’t work with our Nokia N95. It also insisted our home address didn’t exist. Controls for an iPod are built in, but you’ll need to replace the cradle for £50.

All in all, Tomtom’s Go 540 Live is quite an impressive navigation tool that does a lot more than just getting you from A to B, but the price means it’s best suited to those who spend a lot of time driving, rather than casual users.