In my 2008 Infiniti M45S (with Bose system), incoming calls will sometimes get picked up on the Droid X's speaker, not the car's bluetooth system.
It doesn't seem to matter if I use the steering wheel button to pick up the call, or pick it up on the Droid X's touch screen. Incoming audio gets routed to the Droid X's tiny speaker.
Very frustrating!
By the way, I see conflicting advice:
A band-aid fix is to push the speakerphone button on the phone so it goes to the handset and then push the phone button on the steering wheel. I personally confirmed this works.
vs.
When you make or receive a call, click "Use Handset" on the screen in the car so that the call goes to the phone. After, hit the "Phone" button on the steering wheel. Now the call will be transferred back to the bluetooth, the sound will be clear and the other person will be able to hear you.
So which is it? Press the speakerphone button ON THE PHONE?
Or, "Use Handset" on the screen in THE CAR?
I believe it's supposed to be the "Use Handset" button on the car's Nav screen. Here at my desk, I mocked up the Droid X Moto Car Cradle by plugging in power and put my phone over a small magnet to simulate me in a car. I connected a bluetooth headset, and called myself from a landline.
No "speakerphone" button appeared on the Droid X screen. Just ANSWER and IGNORE.
I will try this bandaid in the car, though.