About our car - It is a 2016 C300, only a couple of months old and a few thousand miles on it.

We are taking the car to the dealer to have it checked, but there is a high likelihood they would just say that "everything is normal" and not sure what to do. As I really, really want to get it resolved, I need the advices of the experts here on MBWorld.

Problem observed:
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Initially, the car was very quiet. Very little road noise when we picked it up. We thought it was awesome.

Recently, we have noticed a type of road noise that is quite annoying and uncomfortable.
- It is sort of a constant bass-like sound or a bass hum from the road to the cabin.
- It only happens when the car is traveling (so perhaps from the wheels?).
- It is present on most types of road (freeway, highway, regular street roads).

The only time that it doesn't happen is if I am driving at 25mph or below and let the car glide softly.

It does sound like "road noise." However, it is so prominent, it is very annoying. Also, given that it is kind of a bass-like humming sound from the tires, it is quite uncomfortable to the ears. Several passengers have commented on it as uncomfortable to the ears.

I imagine we are not the only ones experiencing it with our C300.

Could it be caused by:

#1 Run-flat tires (but then again, it was fine when we first picked it up as a brand new car).

#2 Wheels are not properly aligned, hence causing the noise? (but this car is so new and we haven't driven it on any rough road)

Those are the only things I can come up with. I doubt it is #1 since the car was fine and we haven't changed the tires. #2 seems unlikely given how new the car is though.

I would appreciate any advices on what else to ask the dealer to check to make sure this bass-like road noise hum is eliminated...

 

sounds like tire/road noise. This will be difficult to prove unless very obvious.

 

Gonna guess it's the run flats. Common complaints about run flats: expensive, less reliable, noisy.

 

Do you have Burmester? It has a noise compensation circuit that might be involved.

 

This has been mentioned several times here. I hear it on mine now and then. It's road noise/harmonics from the tyres being transmitted via suspension into the cabin.

It will have been there all the time but you've now noticed it and won't be able to UnHear it.

Normal for this car sadly. Some will hear it and some won't. Could depend on tyres, roads used etc

 

Yes, we do have the Continental run-flat, which I understand is the worst offender of all non-flats, though I am not sure how true that is.

Yes, have the Burmester, but I rarely have the speakers on at all.

 

The run flats are noisy to begin with and they tend to get louder with wear. I replaced mine about two weeks after delivery with Michelin Pilot Super Sports. Very quiet tire, and much better ride comfort.