I've always had a plasticy clunking sound behind my left shoulder (seatbelt area) whenever I went over a steep driveway or speed bump. Cars will always have some sort of chassis flex regardless how stiff the frame is and will have its creaks, etc.

As of late..I've noticed it being more prominent just accelerating in a straight line. I'm uncertain if its just normal chassis noise and the plastic panels just popping as it does or something else. Anyone else?

 

Do you have a convertible or coupe? I often hear a plasticy noise coming from my left shoulder in my convertible, and I've traced it to a slight rattle in the panel that covers the roof when it's open. That panel folds up and into the cabin when the roof is raised, and sometimes causes a plasticy clunking noise like you described when the roof is raised. Usually, I reach back and push on the panel and it stops the noise.

 

That might have been helpful information to provide! 2015 Coupe Base.

 

My coupe makes this noise and it appears to be coming from the headliner. I have taken it in once so far and the dealership attempted a fix with some padding which did not work. If I push up on the headliner the noise will go away for a short time. The headliner is short on the drivers side and they have since ordered me a new one. If I drive over 70 mph with the windows down the headliner will separate from the weather strip. I am told my new one should be here middle of May. See this thread. https://www.jaguarforums.com/forum/f...-issue-135263/

 

I'll have to check the headliner when I leave work but I'm almost certain its coming from the plastic trim panels behind the seats. Thanks for the heads up!

 

I have the same sound in my R coupe, but I suspect it's coming from the chassis flex in the pano roof or the hatchback. Never been in a hatch that didn't eventually rattle....hate them.

 

Yep - had a vibration coming from right behind my ear. Almost sounded like it was where the seat belt came out of the side trim. Took it in to the dealer, they dismantled the trim (accessed from the trunk), "reseated a couple of control units" (purpose unspecified), then refitted the trim - noise gone.

Subsequent problem - trim was refitted too tightly resulting in an excessive gap between trunk cover and side trim, causing trunk cover to slide off its hinge pin when the trunk was opened. Took it back to the dealer, trim was adjusted, problem solved.