VW Cabrio 2001 starts knocking under seat above 50 mph

Try reaching under the car and shaking the exhaust around?

That's my guss. you probably have a broken exhaust hangar and the exhaust is hitting something.

Inner CV joint, check the boots first.

You might try premium fuel.

That probably won't cure a knocking sound that's *under the seat*. (Look at the subject.)

CV joints aren't under the seats.

Never assume the person reporting the problem is describing it accurately. My rabbit just started making some front end noises, and one of my CV boots is split. Not sure yet if that is the problem, but I wouldn't put it past a casual ear to misplace where the noise is coming from.

Believe it or not, I did. I believe that the source of a sound can be confusing in cars.

And after 33 years of fixing VW's that where I thought they were! I had a brain fart, and should of asked the owner to check the muffler bearings! I'm giving him a description from what the noise sounds like and not the location.

Precise location of sounds, from the driver's seat while driving, is notoriously difficult. When CV joints and U joints go, the thumping/knocking sound they make gets transmitted throughout the entire car. It's only logical to check out anything that's commonly the source of knocking noises, regardless of where you might think the sound is coming from.

True (i have a wheel bearing problem right now on my A2 but I can't tell if it's right or left via the sound 'cause I'll bet if I sat in the passenger seat while someone else drove the sound probably would seem to "move" I'msure) in many cases. But having experienced the loose exhaust on several occasions due to a broken hangar, that's a very clear sound and it's very clear that it's under the seats. My bet's still on a loose exhaust hitting something under the car.

You're probably right.