The MobileTune looks and feels like a shifter knob, though you'd never accidentally mistake it for your car's because it's short and compact. The 5-inch-long device plugs into the car lighter adapter and a 26-inch cable attaches to an iPod dock connector. Because the knob section has a diameter of about 2 inches, you might have trouble fitting the transmitter into tight spaces, though we didn't encounter any problems. In fact, its compact size makes for easy transport, and it doesn't bulk up your dash area like the dock-style DLO TransPod.
Speck states, "The MobileTune is the model of sophistication in a category rampant with dull plastic devices." While it may not seem sophisticated to everyone, it's certainly not dull. The bottom half of the knob is made of genuine leather, while the control area on top is made of chromelike plastic (almost cheap-looking). You rotate the controller in either direction (the finger grips make this easy to do) to change the frequency on the tiny LCD. While you can tune to every frequency (88.1, 88.2, 88.3...107.9), you don't get a common and useful FM transmitter feature: presets. So if you channel-hop, depending on the area your driving in, you'll have to do this manually. The LCD's size and the fact that it can be difficult to read in daylight add to the chore.
Still, the MobileTune is a top-notch performer with signal strength (and with it, audio quality) that rivals the best we've experienced. Speck product literature states it passe a 70-foot transmission test (rivals are 40 or 50 feet), and it showed. Audio came in at higher volumes and intensity on our preferred San Francisco channel (88.1) than on most other FM transmitters we've tried. Our close secondary channel (89.1) sounded pretty good, too. During a quiet but ultralow frequency bass segment in a song, we did notice an accompanying tone that may be attributed to the transmitter's strength. Final note on performance: Speck claims that MobileTune will charge your iPod faster than other chargers. We'll comment after we test this claim.
While I personally prefer a heads-up model (such as the DLO TransPod), the MobileTune's in-line design maintains a low profile and allows the user an iPod-in-the-hand experience (like using a wired remote control, but please keep your eyes on the road). The MobileTune will work with all dock connector iPods except the 3G iPod. Unfortunately, there is no audio line in, so you cannot connect other audio devices (such as another MP3 player, a laptop, or a drum machine). But the lack of line in and presets shouldn't be a big deal to an iPod owner who wants an affordable and compact FM transmitter/charger.