I like the hood-gap-gasket idea, so I went and scrounged up some rubber weatherstripping/gasket. Of course, when I attempt to test-fit it, it's too small. The gap isn't that big, but the way the hood of the xB is shaped, I can't easily mount what I have.
I guess a trip to Home Depot is in order.
I still need to replace the coroplast in my air dam/grille block with something smoother. That is to say, expanding foam + bondo. Luckily, a significant part of my car is hand-painted in flat black paint, so I can ghetto-rig all sorts of crap and cover it up well.
__________________
|