Performance is also a concern. Though the C520t sits at the top end of Mio's range, it doesn't pack enough punch in the processor department to cope with the demands of the software. Performance while driving is fine, fortunately, but navigating from screen to screen can occasionally be a frustrating experience with a three to five second wait at certain points. It seems to affect the speech engine as well, causing the voice instructions to sound slightly scrambled every once in while. If you remember the sound that agents made in The Matrix when they took over the bodies of unsuspecting bystanders, you'll have some idea of what this sounds like. It's very annoying.
All these issues are by no means the only ones. In testing I noticed many small but nonetheless irritating foibles. Occasionally it would get stuck in '2D' overhead map view, even when it was supposed to be displaying a 3D map. The traffic events list on the information panel didn't update frequently enough, leaving a five minute or longer gap before changing the distance figures. For instance, I drove around the M25 for at least 13km before an incident on the M1 changed from being 130 metres away.
Other irritations include a profusion of small and fiddly buttons for selecting critical functions, and a rather confusing two-pronged approach to searching for points of interest and displaying them on the map.
The trouble with Mio's latest sat-nav is that it's a case of two steps forward, one step back. The widescreen is very nice and Mio has made good use of the extra space, packing lots of much-needed improvements in. Alas, a bit like installing solar panels in an effort to do your bit for the planet while still driving a Hummer to the supermarket to do your weekly shop, these advances are undermined by the introduction of problems that simply weren't there before.
And though the price of £278.63 is reasonable for a device equipped with a TMC receiver, it won't be enough to persuade most consumers to upgrade or choose it over the similarly priced TomTom One XL, which also has a widescreen. I think I'll join them, and stick to my trusty C510e.