The Mpow Bluetooth FM Transmitter is a 3-in-1 device combining an FM transmitter, an AUX-in cord and a phone holder. This Bluetooth car kit plugs into the AC vents and provides a spring-loaded cradle to hold your phone while you drive. In my audio performance test, the audio performance wasn't good, but the phone holder design makes it more functional and less obtrusive than other FM transmitters.
The Mpow Bluetooth FM Transmitter costs $23. This is well below the $45 average for Bluetooth car kits, but $3 above most AUX-in Bluetooth adapters, the preferred technology. While this adapter also features an AUX cord, I couldn't get it to work. I don't know if this was a user error or product error, but the AUX cord combined with the phone holder certainly adds value at this price point.
The audio performance was not good, but this isn't a surprise with FM transmitters. It received a D- grade. Even with it inches away from the stereo's antenna, it had a great deal of static noise. The noise gets louder when the music has lulls or breaks. Even though the best FM transmitter, the Nulaxy KM18, was also poor, the difference was noticeable. The signal strength, however, was just as good as Nulaxy and about 3-dB better than the GOgroove FlexSMART X5, the other FM transmitter I tested. Both FM transmitters reached the same average volume with the stereo's volume set at the same level.
With a poor audio performance while streaming music, the call quality is hardly worth mentioning because it suffers from the same static issues. However, this static is so much worse when making calls because it interferes with the communication. That said, since hands-free calling is not safer than hands-full calling, it's not a significant issue that should make or break your purchasing decision.
The most distinct feature of this Bluetooth FM transmitter is the phone holder. I hesitate to call it the best feature (because of the potential distraction of having a phone screen visible while driving), but it may very well be its most valuable feature. At the very least, it's far less obtrusive than other FM transmitters. Rather than plugging directly into the car charger and using an adjustable arm, it clips into the AC vent and uses spring-loaded arms to hold your phone in place.
The controls, however, aren't designed very well. Most of the buttons are accessible only when the phone is not in the holding cradle. The only accessible button answers phone calls.
The ease of pairing received a D+ because it took the longest for my phone and music player to recognize and pair. Both of my mobile devices didn't recognize the Mpow device for over 8 minutes. During this time, I repeatedly refreshed the Bluetooth search function and found nothing (but other Bluetooth devices in the test lab). Once it finally recognized the Mpow device, my music player failed to pair on eight consecutive attempts before finally pairing. My phone successfully paired on the first attempt, but still took over eight minutes to find.
The Mpow Bluetooth 4.1 FM Transmitter had great signal strength in my tests, but the audio clarity was very poor, though this is expected with FM transmitters. It has an AUX cord, but it didn't work. The phone holder is a unique, less obtrusive design compared to other FM transmitters, but placing your phone so it's easier to see and access also presents a potential distraction.