Model 3

Model 3 Road Noise Evaluation

edited April 2018 in Model 3
Full Disclosure: I am a long-time automotive noise and vibration engineer and live in the Bay Area working at one of the many EV startups (not Tesla). But I did spend nearly 5 years at Tesla developing the NVH behavior of the Model S (and beginning the Model X), so I know well the noise behaviors of these cars. I am happy to say that I just received my own Model 3 (VIN17xxx) and naturally performed some noise benchmarking tests on it. I have access to a Model S P100D (VIN160XXX) and a Mercedes S-550. Below are results of my road noise testing. I test these cars on a moderately coarse surface at 45 MPH (to minimize wind and engine noise), at both the driver's outboard ear and right rear passenger outboard ear locations.

Driver's Ear:
Model 3 - 67 dBA
Model S - 65 dBA
MB S-550 - 61 dBA

Rear Passenger:
Model 3 - 69 dBA
Model S - 67 dBA
MB S-550 - 62 dBA

As you can see, the Model 3 performs well (in general, anything lower than 70 dBA on this road is good), and while not quite as quiet as the Model S, it nonetheless is very comfortable. Of course, the MB S-550 is the champion here and nothing I have ever tested comes close. You'll also notice that the rear seat is consistently louder than the front, but that the S-550 does a better job of balancing that. The Model 3 rear seat does sound a little "open" due to noise coming from the trunk area, but it is not objectionable.

Kudos to the Tesla NVH Team as this is very good performance for a car in this class. I will also mention that wind noise is actually better in my Model 3 than in the Model S I have access to. The door sealing system (especially near the mirror base) is much improved in the Model 3 and it makes a huge difference. Nice job!
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Comments

  • edited April 2018
    Thanks for posting actual data! Much appreciated.
  • edited April 2018
    I'll echo Kathy's thanks. I have heard some people mention the 3 seemed louder than the S. It's good to have actual data.
  • This is a terrific post. Thank you for this very helpful information.
  • edited April 2018
    Nice review, and good info. Thanks.

    What are your thoughts on the benefits of adding sound dampening to the Model 3?

    I usually do at least the doors (Dynamat or equiv., thin closed cell foam to acoustically de-couple, then 1 lb/sf mass loaded vinyl). My Jetta and my Prius have benefited greatly from this.

    In the Jetta and Prius, the floor was also a problem area (rang like a drum) and treatment also brought a reduction in noise. Would that be necessary in the M3 with that dense battery under the floor?

    What about just exposing the wheel wells (peel back carpet) and damping up by the feed and in the trunk? In your opinion does M3 need that or would it be diminishing returns at that point?

    Thanks again!
  • edited April 2018
    feet!
  • edited April 2018
    Two things that improve noise from the rear.
    I put the carpet from my MS in the rear trunk. Does not fit perfect but is ok.
    I put a piece of cardboard in the “window” on the rear deck and put a couple small holes in it to allow some airflow to the trunk.
    You could go a step further and use sound material behind the carpet over the rear wheel wells.
  • edited April 2018
    Nvharmony, do you have any opinions on the wind reduction kit available from rpmtesla?
  • edited April 2018
    I wonder how many hundreds of pounds of sound battening material are needed for the Mercedes-Benz to achieve its result, and whether the current C-Class comes close?
  • edited April 2018
    I find the Model 3 is very good overall for noise and even though I am a "noise engineer" with very high standards, I have no plans to improve the NVH performance of my car. I like it the way it is.

    Just_Ted - Ignoring my comment above, you might find that the Dynamat, foam decoupler and heavy layer makes a difference but it somewhat depends on what Tesla has already done behind the door trim panel. It also depends on how strong that noise path is in the first place. I am not yet brave enough to take mine apart and have a look. As for the floor, the battery pack under the floor pretty much wipes out any noise contribution from the floor in general. This is one of the HUGE noise advantages Tesla has over any car without a large battery pack under the floor. Speaking about "Dynamat", keep in mind that this only provides damping for structural vibrations of the sheet metal, and while this can (and does) contribute to noise, it is only a part of what is needed. Think of it as a necessary but not sufficient part of the solution.

    H271 - My Model 3 (VIN 17xxx) has no wind noise issue related to the windshield gap, so I have to believe this is a build variation problem. If you car experiences this, then the gap seal will work great. Any easy test is to simply tape off the gap on your car and drive around and see if you can tell a difference.

    ReD eXiLe ms us - the S-550 has lots of sound damping materials, probably about 100 lbs worth, and so does the Model S (although perhaps just a tad less). Most cars in that class will have similar sound packages (A8, 750i, LS460, etc.).
  • edited April 2018
    I should also mention that my Model 3 has the 19" wheels with "ContiSilent" tires. In general, lower profile tires are noisier (so the 19's should be slightly louder than the base 18's), but the ContiSilent acoustic foam in the tire should offset that somewhat.
  • edited April 2018
    Is there anything to gain by gathering data at highway speeds, 65+?
  • edited April 2018
    NVHarmony -
    Thanks for the authoritative work. Really increases my anticipation waiting for mine (got a VIN, but don't have a DS).
  • edited April 2018
    One big advantage the Model 3 has over the Model S is that it does not have a hatchback like the S has, and so the passenger compartment is somewhat isolated form the noise generated in the trunk. This was a huge issue for us on the Model S and made getting the car really quiet (e.g. like MB S550) very, very difficult. The Model 3 closes off the trunk (but does have the "vent" in the rear shelf panel), so it can use less acoustical material and still achieve good noise levels.
  • edited April 2018
    jdrsteiny - stay tuned. I may get to that soon :)
  • edited April 2018
    Nice. Thanks, NVHarmony.
  • edited April 2018
    @NVHarmony, thank you this is very informative, and for your past work with Tesla, which I'm sure trickled down into the Model 3.
  • edited April 2018
    NVHarmony: Interesting. I remember reading in an automobile enthusiast magazine that the Lexus LS held something like 200 lbs of sound battening material inside. Of course, that was a couple of decades ago... I suppose they may have used something lighter and hitech since, to help improve fuel economy while still maintaining the serene interior.
  • edited April 2018
    Fantastic report! Thank you so much. I'm just waiting for my invitation, patiently I must add.
  • edited April 2018
    Has anyone experimented with closing off the vent in the rear shelf? I don't have my Model 3 yet - delivery next week :), but I can't help think that this vent is a major contributor to cabin noise. The theory is that it is for allowing bass from the sub woofer to pas through into the cabin, but in my experience that is not necessary. Low frequencies from the sub have no problem passing through the rear shelf / back seats in my current car with no vent.
  • edited April 2018
    Ian.platt - That is something I will probably experiment with on my car as it is easy to do without harming the interior in any way (it is my personal car, after all!). The vent is there mostly for fresh airflow to reach the "air extractors" in the lower rear corners of the trunk. All cars have air extractors (they look like clothes dryer vents with little flaps that close when there is no airflow) to normalize the pressure between the interior and exterior of the car. This is important when you close the doors and when you are operating the HVAC blowers in fresh air mode. The air has to go somewhere.

    Perhaps there is a secondary function to allow the low frequency subwoofer sound waves to come through, but I kind of doubt that since the wavelengths we are talking about are measured in feet, and this opening is too small to have much impact on these frequencies.
  • Great post! I've had my M3 for a week and have been dealing with a whistling noise when i exceed 40mph. I was at the service center today, took them for a ride and they agreed the whistling was an anomaly. He inspected the hood and noticed a small gap where the panel meets the glass (right under the wipers). Quick and easy fix...so something to keep an eye out for, well an ear out for!
  • edited April 2018
    cool fine by me.
  • edited April 2018
    patrick.oconnell - can you give more detail about what the fix was?
  • edited April 2018
    Mr. Harmony,
    Thank you for your comments & sharing you knowledge. My car won't be in for a few weeks, but in my trial run in a friend's car, I found it noisy. I wondered if some Dynamat or some similar type material might help. With your professional scientific background and intimate knowledge of the Model 3, it doesn't sound like it will be that easy to quiet some of the various sources. That said, I will certainly follow your future posts with great interest.
  • NVHarmony - He literally just provided pressure with both hand on the panel (about a 1cm gap) and it kinda snapped back in place. I've now driven about 100 miles and no more whistle sound.
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