whats this metal bar inside the roof

I would guess that it's to stiffen the roof and prevent it vibrating from aerodynamic forces at road speeds.

By the way, why are tearing apart this Prius?

 

<div class='quotetop'>QUOTE(richard schumacher @ Sep 10 2007, 08:08 AM) [snapback]510046[/snapback]</div>

Ditto?
And, do you know what that cable and sensor are for?

I have been thinking about taking down my headliner to find an anoying rattle. Sounds like it is right over the sunglass holder, but it is hard to pinpoint.

Or, maybe I can fill the whole area with some low expansion foam spary. Not!

 

<div class='quotetop'>QUOTE(efusco @ Sep 10 2007, 12:54 PM) [snapback]510135[/snapback]</div>

That it is. The tube runs down the pillar on the right side and along the floor to the front of the car.
Someone posted a while back that they had a water leak on the passenger floor. This tube was probably the culprit.

As for the "bar" in the OP's question, there are actually two of them. Not sure what they're for. My guess is for extra support. Perhaps because the rear dome light unit attaches to that area.

[attachmentid=11335]

 

<div class='quotetop'>QUOTE(prius2go @ Sep 10 2007, 03:44 PM) [snapback]510231[/snapback]</div>

That's actually Damplifier sound deadening mats.
I also added an extra layer of heat insulation to the headliner itself.

I'm sure they're there for a reason. What, I can't fathom.