First off, try posting on mytreo.net -- more activity/Centro users there.

Secondly, you'll need an A2DP software as the Centro doesn't offer this from the factory. I'd suggest Softick Audio Gateway ( Softick Audio Gateway - A2DP wireless stereo headphones and headsets support for Palm OS handhelds and smartphones (Treo 650, Treo 700p, Palm TX, Life Drive, Tungsten T3 and more) ) -- that is what I have and it works pretty nicely.

Lastly ... you'll need either a car stereo with built-in Bluetooth (Pioneer and Sony make good units), or some other way to get the BT audio pumped into your car. I like the Pioneer the best for this, but there are other add-on units that let you retain your factory unit. Any good stereo shop can help ya there. G'luck!