Mio's DigiWalker C320 GPS unit is a slight downgrade to the DigiWalker C520, sacrificing Bluetooth, multimedia functions and internal memory for a cheaper price tag. If you don't require these features, then this is an outstanding unit for its asking price.

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Mio once again uses split-screen technology on the C320 -- the display is split 70/30 with the largest view dedicated to the navigation map, and the other 30 per cent displaying additional information. These include the current time, speed and date, a list of the nearest POI's, traffic information (to be launched in Australia in 2008) and a list of the next four turns in your trip. We found each of these had a significant and positive impact on the overall navigational experience.

The Mio Map menus are a mixed bag. The main screen is excellent, with clearly labelled icons and a text description, but some of the submenus feature smaller icons with no text. The lack of labelling also occurs on the map screen, so icons are small and confusing. The instruction manual is definitely a resource worth reading.

The maps themselves are impressive though and our experience was positive. Mio uses Sensis V14 mapping, and these are preloaded onto the unit's 2GB of memory. An excellent feature is the automatic zoom, which hones in every time you make a turn to give you the clearest possible route. This is excellent at large roundabouts with many exits and lanes, for example.

The C320 is equipped with the popular SiRFstar III GPS chipset and it takes anywhere between 15 and 30 seconds to pick up a GPS signal. The overall navigational experience is pleasing thanks to clear voice instructions and the text-to-speech technology works quite well -- even if it does struggle with some longer street names. Our only complaint is the fact there is no external volume control on the unit. Navigating into the menu to adjust the volume is a hassle we could do without.

When searching for a specific address, the C320 doesn't filter suburbs by state, so you are presented with a list of every suburb in Australia. Once the city is selected, the street name, filtered by suburb, can be chosen. The address entry screen uses an on-screen keyboard and you can switch between standard, QWERTY or extra large layouts.

The usual routing options, such as avoiding tolls, unpaved roads, motorways, ferries and U-turns are all supported. Users can also set a preference for using motorways or normal urban roads, while up-to-date speed camera and red light camera warnings are also included.

The C320 doesn't include a TMC-ready (Traffic Message Channel) cradle or antenna, but you can purchase this separately to use with the unit. The TMC service is set to launch in Melbourne in December 2007, while Sydney and Brisbane will follow in mid 2008, then Adelaide and Perth in late 2008.

The C320's battery lasts up to four and a half hours according to Mio figures, which is satisfactory, but not outstanding.