As a CNET reader who's addicted to tech, you likely already know why a phone and the apps therein can be useful in the car. Your phone is a hub for your music and entertainment, GPS navigation, and communications with your friends, family, and social circles. You've got your apps for streaming music and podcasts from the Web, apps for picking a place to eat or finding the lowest fuel prices around, and your hands-free calls of course. Or, because phones are such personal devices, your handset may bring only a few of these things to your driving experience.
You're in charge of why you'd want to use your Android phone in the car. The tricky part is figuring out how to do it and how to do it safely. Read on.
For the last few years and for most of the Android operating system's lifetime, Bluetooth's Advanced Audio Distribution Profile (A2DP) has easily been your best bet for connecting an Android phone to most newer-model vehicles. This is especially true if you're already making the Bluetooth wireless connection for the Hands-free Profile (HFP) to make voice calls -- using A2DP kills two birds with one stone. Often, A2DP-connected stereos can display artist and title data for the currently playing song and almost always include shortcuts (either onscreen or accessible by steering-wheel buttons) for Play, Pause, and Skip.
Bluetooth-to-stereo audio streaming does have one minor drawback. When you make the wireless connection, your phone and the receiver must negotiate the audio quality at which the music will be streamed. While there is startlingly little information published about how this process works and what specific bit rates and compression algorithms are used, suffice it to say that the audio quality is always less than audiophile-level. What's more, some phones sound better than others, even within the same brand, and there's no guarantee that a phone that sounds good with a Honda stereo will sound just as good with a BMW's, for example. With all but the top-tier premium audio systems, most listeners probably won't notice, but it bears mentioning.
If your car stereo and phone both support pairing for audio streaming, then it should happen automatically when you pair for hands-free calling. Pop into your phone's Wireless settings and locate the Bluetooth menu. Make sure that your phone's Bluetooth is set to On and, following the instructions that came with your car, place the car stereo into its pairing mode.
Tap the "Search for devices" button in your phone's Bluetooth menu and look for your car's ID to appear. It should say something like "Elantra," "NISSAN," or "MYCAR." Tap the ID and, if prompted, enter the PIN that may be given to you by your car stereo. Sometimes you'll be asked to confirm the connection and sometimes the pairing will just happen automatically. You should only have to pair your phone with your car once, with subsequent reconnections happening automatically.
At this point, you'll usually be asked to sync your phone's address book. This is usually a good idea, so be sure to check the box that gives the stereo permanent phonebook access if you don't want to be prompted for a sync every day.
If after this you aren't able to stream audio wirelessly, pop back into the Bluetooth menu on your phone, locate your car's ID, and access its options (either by long-pressing the name or tapping the options slider in newer versions of Android). Make sure that both the Media and Phone audio profiles are checked. If you don't see Media audio as an option, chances are that your car stereo doesn't support it. Double-check your car's manual.
For drivers of older cars or vehicles with more basic car stereos, the humble analog auxiliary audio input (3.5mm TRS) is the next best bet. You'll connect to this simple audio connection with an audio patch cable that plugs into your phone's headphone jack.
The auxiliary input's simplicity makes it the easiest to set up and, possibly, the most future-proof of phone-to-car connection methods. However, this connection is a dumb input, lacking bidirectional communication, so there's no way to control your phone with the car's stereo. If you want to, for example, change songs, then you'll need to interact with your Android phone, which can be less than ideal in a driving situation.
USB is no longer an option (sort of...)
The ability to simply plug your phone into a car stereo via USB is one area where iOS devices still have an advantage over Android (as well as BlackBerry and Windows Phone) devices, even after the great Lightning connector scare of 2012.
Years ago, when I took my first look at methods for connecting an Android phone to a car stereo, USB mass storage connectivity was a shaky alternative method for audio playback of files stored on your phone's micro SD card. However, the method was finicky at best, and too many incompatibilties between handsets and stereos forced me to stop recommending that inconsistent hack.
With the jump to version 4.x Ice Cream Sandwich, along with the switch from micro SD to internal file storage, Android devices also switched from USB mass storage to the media transfer protocol (MTP). (The change actually happened in Android 3.x Honeycomb, but most users didn't really notice it until the Samsung Galaxy Nexus debuted later in 2011 without a micro SD card slot.) The idea was to make Android devices more accessory friendly and to simplify file and storage management. You'd plug your Android phone into an MTP compatible computer and it'd have access to your file system -- no mounting of drives required, just plug and play.
Where the old USB mass storage connection was inconsistent in its compatiblity with car stereo systems, the newer MTP is often simply unsupported. So far, I've only had one vehicle recognize an MTP-enabled Android handset when I, purely by chance, plugged my LG Nexus 4 into the 2013 BMW 135is' USB port for an emergency charge. Much to my surprise, the base stereo allowed me to browse the file system to playback MP3 files stored on the device. It wasn't pretty, but it worked.
Apparently, many BMW models have supported MTP playback going back a few model years at least. Undocumented, the connection method has largely gone unnoticed outside of enthusiast forums while the automaker has focused on promoting its iPhone connectivity. BMW may not be alone in this respect, so we'll keep testing car stereos for undocumented compatibility with Android's MTP connection, updating this feature as we go.
However, I don't expect to find much; automakers seem to be focusing on Bluetooth for now and screen mirroring technologies, such as MirrorLink (which we'll come back to shortly), for the foreseeable future. If your particular car and phone combination happens supports USB connectivity, whether by mass storage or MTP, consider yourself lucky.
Combining methods with adapters
With the aid of inexpensive adapters or certain visor-mounted speakerphones, you can very easily add a Bluetooth or auxiliary connection to many basic car stereos. Products like the Kanex AirBlue and Scosche MotorMouth II plug directly into your car's auxiliary input and convert your Bluetooth audio or calls into analog data your car stereo can digest.
For old cars with a working cassette player, there's the classic tape adapter option, but these devices can sometimes damage the moving parts in your car's cassette deck if poorly made or awkwardly inserted.
Other devices, such the Jabra Freeway, serve double duty, providing fantastic audio for your hands-free calls via Bluetooth and an internal speaker, while also bouncing the wireless audio beamed from your phone to your car's radio for playback through the speakers via FM modulation. There are also FM transmitters that connect to your phone's headphone jack, wirelessly beaming audio to any radio in the area tuned to the right frequency. Of course, FM transmission is notorious for its poor audio quality -- you'll get better sound from devices that connect digitally or directly -- and should be avoided as anything but a last resort, but if you're simply looking for a cheap way to listen to podcasts in an old car without replacing the stereo, this is an option.
Apps and in-car interfaces
Samsung's Galaxy S3 and S4 feature a car-specific mode for S Voice that obeys spoken commands without the driver having to take a hand off of the steering wheel and gives the driver access to only those functions that are appropriate for use while driving. Android phone fans who don't own a Samsung device can replicate the hands-free voice command feature with a third-party app, such as Dragon Mobile Assistant (formerly known as Vlingo), or Google's own Google Now with voice actions.
People looking to add large, easy-to-tap shortcuts to their favorite navigation and audio apps should also check out our lineup of "car mode" dashboard apps.
Stock infotainment options
Most people can't run out and buy a new car just because their current set of wheels is incompatible with their smartphone. However, if you are already in the market for a new ride, knowing which automakers and vehicles are available with infotainment systems that are Android-friendly may sway your ultimate choice.
Through a Bluetooth connection to the phone, Ford Sync AppLink-equipped vehicles give drivers control of a wide range of Android apps using little more than the sound of their voice. At time of publication, there are seven apps that AppLink supports: Stitcher, NPR, Slacker, iHeartRadio, and Pandora for audio, and Scout and Sync Destinations for navigation. Simply say, "Sync, NPR News," and you'll be listening to "This American Life" before you know it.
Hop into a fully loaded Toyota vehicle these days and you're likely to be greeted by the automaker's new Entune interface (or Enform, if you're in a Lexus). This system ties in to an Entune app that is installed on your Android phone, giving touch-screen access to apps such as iHeartRadio and Pandora for audio streaming, MovieTickets.com for browsing and purchasing movie tickets, OpenTable for making dining reservations, and Bing for online destination search.
Pandora Link is found in both AppLink and Entune/Enform as well as the newest Mazda Navigation system, General Motors' MyLink/IntelliLink, Scion's top-tier receiver, certain Hyundai Blue Link systems, and the 2013 Nissan Altima. Beware: although BMW, Mini, and Mercedes-Benz also offer Pandora integration, their versions are currently only compatible with the iPhone version of the app.
All of these Android and app connectivity systems will make use of Bluetooth, because -- as I mentioned earlier -- that's pretty much the only reliable, bidirectional connection that you can currently make with your Android phone. Even the automakers that I haven't mentioned at this point are going to offer some sort of Bluetooth connectivity for hands-free calling, A2DP, or both as well as an auxiliary input as standard or optional features, so look for these basic connections at the very least.
(Honda has debuted support for HDMI video, which many Androids can output, but only for rear-seat video, and then only in the Odyssey minivan.)
Yanking out your stock stereo and replacing it with an aftermarket unit may not sound too appealing, but this is often the best way to add smartphone connectivity to an older vehicle while simultaneously boosting audio quality. In addition to your basic Bluetooth and aux-in setups, the aftermarket is often where you'll see emerging technologies appear first. Pioneer's AppRadio2 is one of the first receivers to support MHL and HDMI app mirroring to give touch-screen access to the apps running directly on your phone, and you can bet that it won't be the last.
The recently announced AppRadio 3 will also support the MirrorLink standard, which will enable owners of certain Samsung and Sony Xperia handsets to simply plug-and-play for touch-screen mirroring. Alpine and Sony are also among the number of car stereo manufacturers that are supporting the MirrorLink standard.
Check out our roundup of the best car stereos for app addicts for more ideas.
Alpine ICS-X7HD mirrors smartphone apps in your dashboard
Other things that you'll need
Streaming audio from the Internet, reading your GPS position, and maintaining a Bluetooth connection can be hard on your phone's battery. If you don't want to arrive at your destination with a flat battery at the end of a long trip, then you'll want to invest in a 12-volt USB charger. However, not all chargers are created equal. The standard USB port outputs about 500mA to 600mA of current, but many of the large-screened, multicored mega phones that have become the norm will scoff at anything less than 800mA to 1,000mA (or 1A). Take a close look at the wall charger that came with your phone for the manufacturer's recommended charging rate and try to match or exceed that number with your car charger.
Beware of 2.1A "iPad" chargers as some of these use Apple-specific variable amperage that renders them incompatible with certain Android phones and tablets. I'm thinking specifically of the Google/Asus Nexus 7. On the other hand, many Android devices work just fine with these adapters -- albeit often at a lower-than-advertised charging rate. As is often the case with cars and Androids, your mileage may vary.
You'll also need somewhere to stow your phone while you drive. If you're using a totally hands-free system like a Pandora Link connection, you can simply toss the phone anywhere (a cup holder, the center console storage bin, or your pocket are all good spots).
However, if you're using your phone for navigation and need to be able to use the screen or to interact safely with your phone because you're stuck using an analog connection, you might want to invest in a phone cradle of some sort. Many phone manufacturers (such as Samsung or Motorola) will offer specific car cradles for their high-profile phones, but they're usually overpriced and won't be compatible with next year's hot phone, so look for a quality universal cradle that uses a suction cup or adhesive to hold your phone to the car's windshield or dashboard.
Avoid those "sticky" or "tacky" dashboard pads that simply hold your phone in place flat on the dashboard with little more than friction and gravity. They may be OK for most driving conditions, but you won't want your smartphone becoming an unsecured projectile in the event of a minor accident.
I've already gone over much of what you'll need to know about using an Android tablet in the car as part of the previous "Transform your Nexus 7 into a car tech powerhouse" feature. Nearly every tip in that article can be applied to any Android tablet on the market.
Possibly the best place for any tablet in the car is in the back seat, and you'll need either a DIY or universal mount, if you plan on hanging an Android tablet from the headrests as you would with a traditional rear-seat entertainment system. I'm of the opinion that, with the exception of very young children, most users would probably be better served simply holding the tablet in their hands, so you probably shouldn't even bother with the mounting unless you're trying to be fancy.