Five FM transmitters for your iPod reviewed

Getting music from your iPod to your car stereo is no easy feat if you don't have an Aux input, which is only now becoming a standard feature. The rest of us are pretty much stuck with FM transmitters, which take your music and rebroadcast it on an unused FM frequency of your choice.

While FM transmitters have never been all that great, new models promise interesting features like automatic discovery of open FM bands, designed to take the chore out of finding an open station.

But how well do they work? I tested five transmitters in San Francisco, where interference is rampant and empty radio channels are scarce. Here are my picks in rough order of best to worst. 

Griffin RoadTrip - My definitive favorite, featuring a flexible neck that holds your iPod upright instead of taking up one of the cup holders or dangling loose in your car. Audio quality was easily the best of the bunch, and the tuning controls double as controls for your iPod (not that you really need them). The large, clear display is easy to read, letting you know at a glance what station you're on.

My only complaints: Auto-tune, as with all of these devices, doesn't work well, and the collection of plastic sleeves (six of 'em), designed to more firmly attach your iPod to the RoadTrip's neck, didn't include one that fit my old 20GB iPod. Fortunately, the RoadTrip works well enough without that sleeve, and this transmitter was the easiest to use and offered the best quality, too. $100

Kensington LiquidFM Deluxe - This is a compact device with the controls all attached to the 12V adapter. Just run the connector to your iPod and put it anywhere. A big, bright display is another bonus. Alas, auto-tune picked terrible stations, and even lots of tinkering didn't help find a good channel to use. Lots of static, but if your stereo includes RDS it will display song info on your stereo while it plays. While this was a distant second-best pick, I oddly found that my older model Kensington FM transmitter worked much better. Strange. $50

Belkin Tunecast Auto - The Tunecast puts its controls on a breakout box along the cable, midway between the 12V adapter and the iPod. But this means the transmitter dips down low in the car, often slipping between the seats and making it tough to fish out when you need it and making for a terrible signal. Auto-tune predictably didn't work, but the display, when you can see it, is nice and big. $60

Griffin iTrip AutoPilot - The iTrip is a lot like the RoadTrip but with the controls broken out, much like they are on the Belkin Tunecast. One cool feature: There is an additional set of controls on the 12V adapter portion, letting you play/pause and skip forward/back, which means you can put your iPod out of sight and still be able to control the music. Good idea, but the radio is underpowered: Lots and lots of static. $100 (not yet released)

Cygnett GrooveSafari - The smallest transmitter of the bunch, this one features all its controls in the piece that hooks to your iPod instead of on the 12V adapter or along the cable. Unfortunately, controls are super touchy (all you can do is change the station up and down) and audio quality is awful, likely due to the tiny size of the unit having room for only a minuscule radio. $50

Bottom line: Only one of these transmitters made the grade for me (the Griffin RoadTrip), and even then I still experience a lot of static when climbing hills and rolling through open areas where ambient FM signals are strongest. I never found an auto-tune system that worked at all, either, but with no other good way to get music to my car stereo, the RoadTrip was at least good enough.

Some advice: No matter what product you pick, try to keep the transmitter as high up in the car as you can, if possible. That's one reason why the RoadTrip works as well as it does, as it eliminates some of the interference between base station and your radio. Happy motoring.