There is nothing better to many people than a long drive, unless there is nothing on the radio, but to get hour after hour of your favourite songs, it is worthwhile to spend a few minutes before the trip to set up a way of playing your digital tracks through the car stereo. The biggest complaint by a real audiophile when listening to music through your car stereo is the depressed frequency range. Fortunately, that can be adjusted to be at least radio station quality, and can approach CD quality, depending on the source tracks. Remember to use both the frequency adjustments (bass and treble) on your stereo's head unit, as well as the frequency profile adjustments offered by your digital music player. With both properly tweaked, most listeners will be satisfied.
The easiest way of bringing your own digital music selections into your car is by burning them to a CD - most stereos built in the past 4 years will play CD-Rs with songs burnt to a regular music audio format - most of the stereos in the past couple of years also play MP3 format tunes burnt to CDs, so you can easily jump from a dozen or two songs to around 150 songs on a single disc. That's certainly a big chunk, but there are other options that can integrate your music player with your car stereo.
The easiest solution, if you have a tape deck, is a cassette adaptor, with one end plugging into the headphone jack on your player and the other is inserted into the stereo like a regular cassette. The sound quality is not too bad, there are no options to fiddle with, and you can easily bring it when you change vehicles, so considering the cost, you can't go wrong. The drawbacks are that you need to have a cassette option for your stereo, obviously, and you're stuck if you don't have one.
The most widely compatible option is an FM transmitter adapter, like the iTrip or TuneCast, which plugs into the earphone jack on your player and transmits the music to a programmable radio station you can then listen to in the car. The good news is that these adapters work wirelessly, so no cabling hook-ups, and no problems switching to another car. The bad news is that the sound quality suffers slightly by being broadcasted this way, and when travelling through different city centers or areas with a large number of FM radio stations, you may find that you are frequently reprogramming the unit to new stations to keep listening to your tunes.
The option that provides the best quality and features is a wired adaptor, like the IceLink or even a simple 1/8" jack wire depending on the stereo model and brand, which attaches to the back of your stereo's head unit. It may take a little time and skill to hook it up, perhaps 15 minutes to an hour depending on your car, but once it's done you can get a very high quality hook up - many models will also take advantage of control buttons on your steering wheel, charge your music player while playing, and can even pass the ID3 tags from MP3s, bits of information like the artist and song title, to the stereo to display on the stereos screen. These are definitely nifty gadgets, although they are going to be more expensive than an FM transmitter and are not as transferable to a different car.
