Any ideas on what this outer wrap is on the intermediate driveshaft? Possibility: a damping material to cut down on torsional vibrations, at first I thought it might be carbon fiber layup to increase torsional stiffness, but that seems a bit exotic for a factory HHR.

 

I don't think it's anything other than black paint. The F40 six speed setup I have for my beretta has nothing on the intermediate shaft but paint. I see no advantage to a dampening material placed on the short shaft that is supported securely at each end. If anything they would dampen the half shafts, but just my

 

You are probably right, it just appears to have some considerable thickness to it. Not sure why they bother to paint that one and not the half shafts if that is all it is.

 

rubberized paint. same on my Cobalt SS
start soaking those bolts now for the downpipes coming out lol