First of all, you should soundproof the following areas in your car:
Floor: The floor of the car cabin is one of the main sources of external noise penetration. Installing sound insulation materials on the floor will significantly reduce the noise level inside the cabin.
Doors: Noise penetration through the doors can be significant, especially at high speeds. Installing sound insulation materials inside the doors will help reduce noise from passing vehicles and wind noise.
Roof and pillars: The roof and pillars of the car can also be sources of noise penetration. Installing sound insulation materials in these areas will help reduce noise that enters from above and from the sides.
Hood and engine: The engine can also generate a lot of noise, especially at idle or at high revs. Installing sound insulation materials under the hood and around the engine can help reduce this noise.
Trunk: If noise from vibrating objects in the trunk is often heard, installing sound insulation materials in this area can help reduce this effect.
According to https://shumoizolyatsiya.com.ua/ these are the main areas that should be soundproofed first in a car to improve comfort during rides.
