I have a 2000 Jetta, 160,000 miles on it.
I’ve had some sounds that concern me coming from the underside of the car, however I can’t really pinpoint where they’re coming from while driving.
To me, it sounds like an exhaust leak should, a low, loud “buhp, buhp, buhp”.
However, the only time I can get this to occur on a regular basis is while turning and accelerating. This does it pretty much anytime, … although not all the time.
That said, I’ve also had it make the sound once while parked, first thing in the morning when it was really cold, it happened for a few seconds, then stopped.
The fastest, easiest, cheapest, and most confident way to find out what’s wrong is to go to a local muffler shop and ask them to put the car on the lift. Estimates are free at most places. Even tire stores offer this service. Once you know what’s wrong you can decide on a plan. Until then…