Clanking sound from undercarrige
 

Q7 2009 with 110k miles. I can hear a single metal "clank" when I drive over a bump or hit a hole in the road; I think it happens mostly at low speeds but I could be wrong. I can only hear it when I have the front windows open and near a side wall(building or cars parked) so the sound can bounce. It sounds like a pipe that is loose in the clamp. I also have an occasional error code about the EVAP system that shows up once and a while and then disappears; no idea if it is related. Happens on all tires. I've been to two mechanics that couldn't find the source. One of them said that he thinks it is the struts; all of them failing at the same time? Any ideas guys?

A clang sounds exhaust related like a heat shield, just inspect it to see it one is loose.

I took it to a third guy and he couldn't find a problem with the undercarriage. The definitely hear the clang only at low speeds; I drove with the windows down near the divider on the highway and couldn't hear the clang. Does that mean a problem with the suspension? The car has been driven mostly in NY and NJ; the roads are terrible around here.

The problem could be the tie rods. I had the same problem on my C350. Here is what I would do. Jack up the front and the vehicle and check the front wheels by grabbing the wheel at 3 and 9 o'clock and push and pull on it to see if you feel any play. And then do the same thing to the rear.

Here is a good Youtube video.

Take a look at the sway bar. It is a common Audi problem as the mileage gets higher.

Center bearing on driveshaft, get under the vehicle.. its right in the middle of the vehicle.. give it a good shake and see how much it moves, its a common failure.