Information: 2016 TLX 2.4L Tech Package, purchased around November 2017 as a demo car with around ~7000KM on it. Currently has 13000KM on it.
The vibration is gentle throughout the cabin and most of the time you can feel it through your steering wheel and middle/top parts of the driver seat during idle or stopped at red lights. The vibration stops/lessens after putting in some gas to the car but comes back when fully stopped.
During startups, the vibration is the worst, and sometimes you can see the logo on the steering wheel shake, but calms down a bit after driving the vehicle for around 5mins. Every time passengers opens the doors, you can hear a rumbling sound throughout the cabin. The rumbling sound feels like opening windows where the bass is hurting my ears. The sound in the cabin is more vigorous when I open the passenger door and trunk together. I tried this in Park, Reverse, Neutral, and Drive but it still causes this problem.
I brought it back to the dealer a couple times and they said they couldn't find anything to fix, and told me to worry about nothing since its not causing damage. But the thing is, I didn't think Acura would produce this kind of quality cars. I even tested the vibration on my dad's 08 Kia Rondo and theres is some vibration coming from the steering wheel but not as bad as my 16 TLX. Could this be a transmission problem? I know that TLX has a transmission problem.