How to make your car cabin quieter | Car soundproofing tips

Even if your car cabin is not soundproof, you should know that there are materials and solutions to solve this problem. Using the right stuff and a few hours of your time, you can make your cheap or old car as quiet as the expensive cars.

Why are some cars a lot noisier than others? 

Even when we analyze new cars, it turns out that a lot has to do with the insulation that the manufacturer either put in the car or, in the cheaper cars, didn’t put hardly any in.

For example, we tested and compared two randomly used cars, a Lexus and a Toyota Matrix. We used a classic decibel meter and drove around the neighbourhood to see the cabin’s minimum, maximum, and average sound levels. You can see the table’s values, the first test with Lexus and the second with Toyota.

CarMin LevelMax LevelAverage
Lexus41.7 dBA48.0 dBA44.85 dBA
Toyota45.8 dBA68.9 dBA57.35 dBA

It turned out that Toyota is a lot louder car and a lot of that noise comes from a lack of insulation. Inside the door panels, there is no real insulation. So, we decided to solve this problem and tried to make Toyota a quieter car.

If you knock on Toyota’s door on the outside, you can hear the echo confirming that there is a space. The same action on Lexus, and you can listen to a much more solid sound; it’s not as tinny because there is some insulation inside.

But guess what !? You can add insulation to your car – that’s the secret and the first step to turning an ordinary car into a luxury car 🙂 

Car floor insulation

Are you looking for sound-deadening materials for cars? Read an excellent automotive deadening materials article here and learn how to soundproof your lovely cars.

There are various layers of insulation and soundproofing that you can add to your vehicle:

  • hood insulator
  • moulded headlining
  • heat shield 
  • dash and dash outer insulator
  • engine top cover and undercover
  • transmission insulator
  • vibration damping sheet
  • floor carpet
  • wheelhouse protector
  • rear parcel
  • retractor insulator.

For instance, for things like the inside of your trunk, there is an excellent thick lace stuff that fits in, it compresses fine, and it will really quiet the noise down for when you’re driving down the road. This product does a good job, especially at highway speeds when you get a lot of tire noise and other cars’ vibration noises. It is self-adhesive backing, so it sticks on pretty well.

How to soundproof a car | Soundproofing tips

Of course, it sounds simple but putting the insulation in is not a two-second job. In this case (insulating the trunk), you have to follow the steps:

  1. take the whole plastic panel off
  2. use isopropyl alcohol to clean it all off, all the metal area
  3. stick the insulation on
  4. cut the insulation to make sure it fits
  5. put the plastic cover back.

Sure, putting the insulation up inside is a more straightforward job because it’s all in the open, and the trunks are easy to do.

Door soundproof

To insulate the doors, you have to :

  1. take the panel off
  2. cut the insulation to fit inside 
  3. put it on the skin, on the far side
  4. mount the door panel back on.

The real fanatics will even take the top of the car off, inside, take the liner out, put insulation in and then put the liner back on to make it even quieter. Removing the seats and the carpeting will stick the bottom insulation on. 

Yes, it’s labour-intensive, but this is the way to go if you want a quiet car.

On Matrix, we added insulation inside of the doors and trunk only. In the end, driving on the road and testing with the decibel meter again, the results were: min= 36.3 dBA and max= 54.1 dBA. So, both readings were lower.


If you want a quieter car or you are an audiophile who wants a sound system to sound as crisp as possible inside the vehicle, you might want to try some of these sound-deadening materials for cars.

If you’ve ever seen those lowrider cars with a giant mega-bass in the trunk … the cheap ones … you hear them rattle like mad. But, the good ones, they used all this sound insulation in the trunk and all over the car, and it doesn’t rattle – they got a loud and crisp sound.