One welcome feature is the addition of text-to-speech functionality. This means the Mio C520 will now speak actual street names, allowing you to pay more attention to the road rather than the map screen, because you get more precise audible prompts. You also have your choice of 14 language and voices, but you can only get text-to-speech directions in English. To complement the voice-guided directions, there's a new split-screen view that displays various details about your trip. You can cycle through several views that give you the distance and direction of your next turn; a list of upcoming turns; nearby gas stations; current time; estimated time of arrival; speed; and more. There's an option to hide this panel altogether if you find it too overwhelming and just want to rely on the map and voice prompts.
With the integrated Bluetooth, you can use the Mio C520 as a hands-free speaker system for your Bluetooth-enabled cell phone or smart phone to receive and make calls. For outgoing calls, you can use the onscreen dial pad or select a contact from the device's phone book. Also, if a POI has a listed number, there's an option to dial out directly to that business. Unfortunately, you can't wirelessly transfer contacts from your mobile's address book to the C520, and call history synchronization isn't available on all phones. (See Performance for more.) A nice and unexpected bonus is that the unit works with Bluetooth stereo headsets (A2DP profile).
The Mio C520's media player is basic (though you get equalizer settings and playlist creation) and as we mentioned earlier, the interface is somewhat confusing and bare-bones. Still, you can learn to work with the player; the bigger problem is that the system doesn't always work with all supported formats. Mio says the C520 can play MP3, WMA, WAV, WMV, AVI, and MP4 music and video files, but we weren't able to view any WMV or AVI movies. Mio does include Ulead video converter software, however. Clearly, the most important function of this device is its navigation tools, but with the sleek design and large screen, we could have seen ourselves occasionally using the C520 as a portable video player, so the limited support is disappointing.
We tested the Mio C520 in San Francisco, and from a cold start, it took about three minutes to get a satellite fix under cloudy skies. Subsequent starts took anywhere from a few seconds up to two minutes, but once locked on, the GPS receiver did a good job of holding onto the signal as we drove throughout the city. We did notice, however, that the system was about half a block behind us when tracking our location. We also entered our standard trip from the Marina district to CNET's downtown headquarters, and the C520 quickly returned with accurate directions. The text-to-speech voice directions were helpful and detailed; the female voice was a bit robotic but we had no problems understanding her. We also missed several turns to test the route recalculation rate, and while the system was fast to give us a new and precise itinerary, we didn't find it to be very efficient. There were times when we knew a more direct route than the one recommended by the C520, but if you're completely new to an area, the C520 can be a lifesaver, getting you back on track to your destination.
For Bluetooth compatibility, we connected the C520 with the Palm Treo 755p and HTC S710 smart phones. We had no problems with the pairing process, and we were able to make and accept calls. However, we couldn't synchronize our call list from either phone. Multimedia performance was mixed. Music playback through the unit's speakers was surprisingly good with plenty of volume and richness, but again, we wish the C520 had a 3.5mm jack so we could plug in a nice pair of headphones. Watching an MP4 video clip was a less satisfying experience, as images often looked pixilated. The Mio C520's 1300mAH lithium ion battery is rated for up to 4.5 hours of GPS use and up to 8.5 hours of MP3 playback with the backlight off.