Car interior noise measurements (german automobile club)

[pavuol]

German automobile club ADAC has a long tradition of publishing quite uniform car reviews. What is interesting from the ASR’s perspective, they include measurements of interior noise level while driving.

Here is complete list of all reviews in pdf files (around 4000+ this time). As the time range spans several decades back, the most older reviews don‘t have acoustic measurements at all, some from the “middle” period include measurements at three particular speed levels (50, 100, 130 km/h / ~ 31, 62, 81 Mph) and finally the ones from the recent period have measurements only for 130km/h speed.

Here is a pdf file for their metodology. For acoustics it states (free translation):
Interior noise
Measurement of the sound level in dB (A) at head height in the middle of the vehicle at 130 km/h (stock summer tires). Several measurements are carried out and an average is formed. Due to the additional subjective assessments of wind, driving and engine noise, the overall grade of two vehicles with identical noise levels can be different.

So as you can see, each review includes an objective value in dB as well as written subjective assessment.

To make it a little more fun I picked up several interesting cars and put them together in a table, based purely on the objective noise value . To no surprise, the quietest cars are luxurious limousines. On the other side of spectrum there are some sport cars/offroad cars. I decided to give some awards as well, just don't take it too serious, each tier is based solely on dB value not taking into account other aspects of each car .

PS: of course I didn't went through all the reviews so feel free to post some interesting findings.

"tier 1":

"tier 2":

"tier 3":

"tier 4":

"tier 5":

"tier 6":

Spoiler: table screenshots

sorted by manufacturer-brand:

sorted by noise level:

 

[Willem]

Fascinating, as I really hate noisy cars, both from the inside and from the outside. The biggest surprise for me was the 73 dB score for the Fiat 500 two cylinder turbo. So it is not only a beautiful town car, and frugal, but also quiet. For the last few months we have benefitted from new ultra quiet electrical busses in our town, and the difference was a pleasant surprise. And we no longer have to suffer the diesel fumes.
As for the 130 km/h speed used for testing, all I can say is that the Dutch government has just reduced maximum highway speed during the day from 130 km/h to 100 km/h in an effort to reduce emissions. With our car we noticed about 25 % lower fuel consumption compared to 130 km/h on long trips, and rather more relaxed driving. And I am sure less noise, but our car is not on the list.

 

[LTig]

I checked a number of those reviews recently because my car is nearing its end of life. I noticed that often the subjective review how the car sounds inside does not correlate well with the measured noise but more with the price of the car. Reminds me like stereophile reviews.

 

[FrantzM]

Hi

There a few surprises for me:

Electric cars didn't dominate
Cars with Diesel engines were among the quietest. Actually the #2,3,4,5 quietest cars were Diesel on your chart!! Wow!

Very interesting tests... Can I share it with my car enthusiasts friends?

 

[Willem]

And 130 km/h is only a partial measure because at that speed most noise will be wind noise, plus a bit from the tyres. In urban traffic with a lot of stop and go engine noise is likely dominant.

 

[pavuol]

I checked a number of those reviews recently because my car is nearing its end of life. I noticed that often the subjective review how the car sounds inside does not correlate well with the measured noise but more with the price of the car. Reminds me like stereophile reviews.

Didn't look at them much but I can imagine pure decibell value can also be not that informative, for example we don't know what frequencies dominate, what is measured spectrum range etc. Maybe some resonances ccould be not that loud but quiete annoying subjectively

 

[pavuol]

And 130 km/h is only a partial measure because at that speed most noise will be wind noise, plus a bit from the tyres. In urban traffic with a lot of stop and go engine noise is likely dominant.

I would say engine as well but especially for cars with fewer/shorter gears which spin their engines at high rpm at 130km/h.
Also I think many scores would look quite different, been particular models equipped with "stock tires" of quieter type.

 

[pavuol]

Don't know how about U.S., but here in EU we already have tire labels featuring noise rating:

Spoiler: tire label

 

[Willem]

A year and a half ago we bought a low mileage Peugeot 406 with cheap summer tyres.This Spring I replaced them with high quality summer tyres and not only does the car now handle a bit better, but it is also a bit more comfortable and quieter.

 

[Soniclife]

Didn't look at them much but I can imagine pure decibell value can also be not that informative, for example we don't know what frequencies dominate, what is measured spectrum range etc. Maybe some resonances ccould be not that loud but quiete annoying subjectively

They are at least using a weighting, but I expect low frequency noise still dominates these readings. I did a very limited and low quality test on my car at 50mph, the app on my phone didn't register any change with the stereo on or off, at the volume I usually listen to it.

 

[Soniclife]

And 130 km/h is only a partial measure because at that speed most noise will be wind noise, plus a bit from the tyres.

My impression is that's more the other way around, the tyre noise is the dominant source. From a pedestrians viewpoint an electric and petrol get similarly noisy from fairly modest speeds.

 

[LTig]

My impression is that's more the other way around, the tyre noise is the dominant source. From a pedestrians viewpoint an electric and petrol get similarly noisy from fairly modest speeds.

Yep. I changed tires due to the old ones run down, and although the new ones are the same brand and series (Conti Premium Contact, just a newer model) the car is now quieter.

 

[Willem]

Conti Ecocontact 6 in my case.

 

[tomtoo]

At 220km/h the dominat noise is the wind. At least in a cabrio.

 

[Willem]

Here it will be the police sirens, and then probably the big metal press for impounded cars.

 

[Wes]

There are good noises and bad noises.

Bad noises come from wind, and the tires.

Good noises come from a fla 6 or a flat crank V8, a V-12, etc.

 

[tomtoo]

There are good noises and bad noises.

Bad noises come from wind, and the tires.

Good noises come from a fla 6 or a flat crank V8, a V-12, etc.

Nah, wind is a good noise.

 

[Nango]

ADAC ist also known to use no scientific methods in the heir reports, often inclined in favour of german brand names paying big ads in their magazines, so ........I wouldn't give that much on their words.