With an in-dash unit like those that Dynavin makes, you can Bluetooth or Wi-Fi tether your iPad, tablet or smartphone for your GPS unit. With Bluetooth tethering you are able to listen to any of the music you've on your phone through your vehicle’s sound system and, it consumes less battery power than Wi-Fi tethering. Many in-dash GPS systems have built-in microphones, or in the case of the audi navigation system, a high-quality one, meaning you may make hands-free telephone calls using your Bluetooth-tethered in-dash unit. Wi-Fi tethering, however, enables you to access radio or videos on the internet but enjoy them through your in-dash unit. When your phone and unit are tethered you can take control of your media on your in-dash screen. Also, many smartphones have several battery-saving choices for Wi-Fi tethering which means this should not be a lot of an issue. With Wi-Fi you're essentially only restricted to what is available online. Maybe you forgot to download a brand new song you want and want to look it up on YouTube or, maybe you wish to stream live radio from another area-you can do all this with Wi-Fi tethering. You may also pull-up maps through your GPS interface with either, Bluetooth tethering, or Wi-Fi tethering. If you have an apple iphone it might be more convenient to do this via Bluetooth since with it, you are able to sidestep while using Personal Hotspot. Establishing your smartphone, iPad or tablet for tethering together with your in-dash navigation unit is relatively easy and there are a variety of sources on the internet that offer step-by-step introductions regarding how to achieve this. Enabling Wi-Fi and Bluetooth tethering has a lot to offer but make sure of your carrier’s terms and regulations because some may limit (legally) what you can do, otherwise, enjoy all the features at your disposal involving the in-dash unit and smartphone from Dynavin!