If you regularly use your cellphone in the car, but so far have been reluctant to either fill the cabin with wires from an untidy aftermarket kit or are disappointed with Bluetooth headset performance, Sony might have the solution for you.  The MEX-BT5100 is a replacement head-unit, with the usual radio, CD player and MP3 CD compatibility as well as Bluetooth and an onboard phonebook for use as a hands-free speakerphone.  Since it’s all wired in, it’s a tidy way to add functionality for those who didn’t fancy shelling out the big dollars for a manufacturer car kit (or who didn’t buy their car brand new).

CNet have been putting the BT5100 through its paces on the open road, and come away impressed; rating it ‘Excellent’ (with a score of 8.3 out of 10), they praise the straightforward control – via a joystick and sturdy, tactile buttons – a clear and easy to follow GUI, and ID3 compatibility to show MP3 track information.  Not so great, however, was the 50 contact phonebook limit and the slow scrolling through that list; for some reason holding down the joystick doesn’t speed through entries, so you have to tap it down past each one.

Still, with great sound quality (both of music and in-call) and A2DP for streaming music from a Bluetooth PMP or handset, the MEX-BT5100 seems like a pretty good way to spend $330.