Ticking noise in dash

2002 VW Golf diesel. 70M. Coming back from a trip a loud ticking noise occurred seemingly behind the driver’s side dash. Seems to happen at 65 and above only. Intermittent. Slowing stops it. Not slowing and it goes away. It is constant in frequency and can vary in loudness. Does not seem to affect operation of car. May be in engine compartment. I would swear it is worse in a head wind. What is it?

One clue that makes me think this is the “worse in head wind”. Could be a door vent flapping.