Look in the tascaparts.com on line catalog under "steering" for your car. I think you'll find that is the high pressure hose (from pump to rack) for the steering - the drawings will help you identify the hose and the part number.

Have you checked for vacuum leaks?

Do you know if the car was in a collision or flood before you bought it?

My 2009 S80 Exec has adaptive cruise from factory.

The 2008 model year had that option available. See the video:

I imagine it could be retrofitted but not sure how. My guess is, it's a much bigger job than adding CC to say a late 80's 240 or 740.