What Car? guide to portable sat-nav - MIO Digiwalker c710

Cost £359
For Light, user-friendly
Against 'Speed control' function is a bit eager
Verdict Plenty of functionality, convenient destination search

This light, pocket-friendly unit multi-tasks as an MP3 player, calculator, contacts book and photo library.

It scores well for ease of use, and a panel on the left side of the navigation screen holds all the important information for your journey. You can opt for a full postcode search, which is the most convenient, or by city and then street (there's a predictive function which means you don't always have to type the full name).

The Points of Interest function seemed geared towards chain-type restaurants and the 'warn when speeding' function repeatedly told us we were over the limit when we weren't. Similarly, the speed limit warning icon was frequently incorrect. However, free updates of speed camera locations are available for a year.