Pretty much every new car you can buy today has an auxiliary input and standard adoption of Bluetooth hands-free calling and audio streaming growing consistently with each generation. So, with the right mix of apps and a bit of restraint, you can use pretty much any new smartphone to do basic things like listen to music or make a call safely behind the wheel.
However, a handful of phones go above and beyond these basic functions, offering automotive-specific interfaces, advanced voice commands, dashboard app mirroring, and more. We took a look at the most popular smartphones on CNET and picked out, in no particular order, our favorite driver-friendly models and features.
Samsung Galaxy S4
I'm a plain vanilla kind of Android enthusiast, so I'm not a huge fan of third-party rejiggerings of the stock Android experience. That said, Samsung's S Voice voice recognition and the companion S Drive interface are exceptionally well-suited for use in the car. Though not as flexible as Google Now or Siri, S Voice can be set to an always-listening mode where it will respond to your commands without the need to touch the device.
Simply say, "Hi, Galaxy," and the device will spring to life ready to accept your requests to navigate to a destination, initiate a call, or send a quick text message or e-mail.
The S4 also gets our nod for its support of MirrorLink connectivity, which enables the handset to work with app mirroring touchscreen receivers such as Pioneer's AppRadio 3 and the Sony XAV-701HD. However, we've seen reports around the web that the MirrorLink connectivity can sometimes be fiddly.
With a few exceptions, the iPhone 5S, the 5C, and 4S is pretty much universally compatible with every car stereo (OEM and aftermarket). Just jam the business end of its USB adapter cable into any car's port and it's almost guaranteed that you'll be able to browse and play back any audio media stored on the device; no setup is required. Any supported app integration usually makes similar use of the USB connection, so you won't have to pair your phone with your buddy's Bluetooth to listen to your Pandora stations in their new Kia Soul.
However, the iPhone's biggest strength is, well, that it's the iPhone. The device's ubiquity and uniformity means that automakers and aftermarket hardware manufacturers will often develop for Apple products first when looking to experiment with new features or connectivity -- expanding to support other OSes later, if ever.
For example, Pioneer's first-generation AppRadio only worked with iPhone, with Android compatibility coming in the second-generation. The BMW ConnectedDrive app system only worked with iOS for years, only recently adding Android integration. (Its Mini Connected counterpart, to this day, only works with the iPhone.) Most recently, we're seeing a wave of automakers boasting hardware compatibility with the iPhone's Siri Eyes-Free voice assistant system while being curiously silent about Google Now.
Motorola Moto X
The Moto X lacks specific Car Mode software, but the handset's unique Touchless Voice command and tight Google Now integration make up for its lack of a dedicated car mode. Simply by speaking the words "OK, Google Now," you can input a destination for Google Maps Navigation, fire off an "I'm running late" text message, and queue up a driving playlist.
With the full flexibility of Google Now behind it, the Moto X can also be commanded to set reminders, save short notes to yourself, read sports scores, and more. Few phones allow you to do so much without removing your hands from the wheel to touch the screen.
Nokia Lumia Icon
The Windows Phone-powered Lumia Icon (and its cousin the Lumia 1520) also make available a Car Mode interface that puts shortcuts to car specific functions front and center with large, easy to hit tiles. When it comes to navigation, the Lumia features Nokia Here Drive navigation, a gorgeous and competent alternative to Google Maps and Apple Maps.
Our editors praised the Lumia Icon's AMOLED screen for its exceptional outdoor visibility and glare resistance, which will come in handy when you've got that 5-inch display suction-cupped to your windshield or dashboard.
Though the Windows Phone operating system doesn't enjoy the same level of OEM and aftermarket support for things like app integration, a user can still get a lot safely done behind the wheel with just the standard Bluetooth hands-free calling and audio streaming connections.
Like the Samsung Galaxy S4, the HTC One's modified version of Android boasts a Car Mode of its own that can be triggered manually or by placing it into certain car cradles. When in Car Mode, you'll have quick access to large shortcuts to navigation, favorite contacts, and other shortcuts relevant to driving.
There's also a dedicated button in the Car Mode interface for the HTC Voice Assistant software. While not as flexible as Google Now, it's at least as functional and accurate as the S4's S Voice system and will do pretty much everything you need while driving.