It’s hard to get away from the TomTom Go. It’s by far the most popular satnav device in the UK and is in hi-tech shouting distance of Apple’s ubiquitous iPod. Everyone seems to have one. But therein lies the rub.

For part of the reason TomTom posted an 83 per cent drop in profits this week is that most people who want a satnav probably have gone and bought one, and around half of them have plumped for a TomTom Go.

All TomTom can do now is defend itself against a growing number of rivals by dropping prices (it looks pretty secure on that score) and then keep adding features to persuade people who own older satnav devices to upgrade to the new one - features like music and photo playback that nearly every PND maker seems to have, but can’t adequately explain why.

Of the new ‘must-haves’ in the TomTom Go 920 T, MapShare sounds more interesting that most. It enables you to log any road layout of other changes on your device and then share them with other drivers via the TomTom Home 2.0 software you install your a PC or Mac.

Of course MapShare enables you to download changes logged by other drivers too, helping you ensure your maps are up-to-date while you wait for a major update from TomTom’s map supplier TeleAtlas.

Voice recognition

The other ‘big’ new features are more of a mixed bag. Like the TomTo Go 720 T, the 920 T also includes voice recognition software that enables you to bark commands at your TomTom, rather than enter them by hand.

It would be great if it worked as well as advertised but, like every other voice recognition system ever invented, the reality is it's a lot less certain to recognise your well-rounded vowels, forcing you to eventually abandon the idea. Like the 720 T, the 920 T also includes text-to-speech so you can hear text messages sent to your mobile phone, without having to pull over and read them.