TomTom has introduced a new user interface to its top of the range portable GPS units in Australia.

The company has announced the new GO 500 and GO 600 portable navigation units and claims the new software is significantly easier to use than competing devices.

TomTom Asia Pacific's vice president and managing director, Chris Kearney, said the user interface changes bring the new GO units into line with the latest smartphones and tablet devices.

"People are used to interacting with maps and having a map do something when they touch it, so we have put the map at the heart of the user experience," he said.

"To us the map is key to the device, and what we've done is really make it interactive. I can touch and point on the map and do something straight away. It's what people expect from a digital device now."

TomTom has stripped away the traditional address entry search on the software by introducing a quick search function.

The capacitive touch screen on the GO 500 and GO 600 also offers pinch to zoom functionality typically seen on smartphones and tablets.

In addition to the new user interface, both the GO 500 and the GO 600 include quarterly lifetime free map updates, lifetime traffic updates, and 3D city maps.

The traffic updates are enabled by tethering the GPS to a data-connected smartphone via Bluetooth.

TomTom says the service will use around 5MB of data per month based on around an hour of use per day.

The company also confirmed that the pre-existing ability to correct maps, called Map Share, is "coming soon" to the new models, but the feature won't be available out of the box.

The new units are identical aside from screen size. The GO 500 has a 5in capacitive touch screen while the GO 600 has a larger 6in display.

TomTom hopes the new GO devices will reverse a decline in the portable navigation market in Australia, though the company says it still expects to sell close to 700,000 units this year.

The TomTom GO 500 ($249) and the TomTom GO 600 ($299) are available now through "leading retailers" across Australia.