jagman78

I have a 2001 S8 that just turned 100K miles. Sometimes when I am slowing down, not at a complete stop and I accelerate I hear a loud bang come from the rear of the car. This will also happen if I am on a hill, roll back, and accelerate. Otherwise the car shifts smoothly when going through the gears. No check engine light or transmission light.

nyrobbie77

Could be a lot of things. spare tire/jack/battery loose in the trunk? dead body rolling around in trunk?

underneath could be loose suspension bushing which is probably the issue.

could also be worn cv joint on the prop shaft but they usually just make a clicking noise when they start to go. here's a link to the sound my cv joint (prop shaft at trans output) was making when it went cv clicking noise

also could be the center support bearing on the driveshaft is worn/torn

Without hearing your noise or experiencing it, it is difficult to determine what it may be. Start with the easy stuff by checking for loose objects in the trunk. Then move onto jacking up the vehicle and checking out the suspension bushings.