For many of us these days – myself included – smartphones and MP3 players have taken the place of our car’s built-in stereo system. More and more auto manufacturers are recognizing that fact, and are building compatibility with such devices into their vehicles. Ford’s SYNC system, for example, can connect with an iPhone via Bluetooth and allow the driver to control music playback and make phone calls using either voice commands or the car’s stereo controls. Many of those systems are imperfect – for example, SYNC can’t interface with the iPhone’s music controls via voice command. Moreover, many cars don’t have such systems. If you drive one of those cars, getting your phone or iPod’s music onto your stereo requires a little extra work – an AUX jack, an FM transmitter, or a tape deck adapter. And then, once you get your phone hooked up to your stereo system, actually controlling music playback can be difficult, and even hazardous.…