Many cars have an annoying high noise level. Silence here is important for long driving and signs that the car manufacturer has taken this into account.
Strangely enough, the cars were quieter before, as we emphasized this much more. The reason is the need for more sporty driving, stiffer springs, fatter tires, thinner walls and floors and saving space. The use of diesel gives more engine noise in uneven driving, but on the motorway it is slightly lower due to lower engine speed.
In the "old days" great emphasis was placed on comfort during quiet driving. Think of the 30s where Rolls-Royce claimed that the highest noise was ticking the clock. Owners of Mercedes recall and, for example, the C-180, which in the 90s was much quieter than today's models.
In different ways this can be reduced by using a 3 mm Acoustiblok.
Some listen to music from door speakers that are spoiled by road noise from the outside. One can dress the doors inside but save out openings to the speakers and use Acousticaulk noise mounts around.
Glue on walls / covers with either 3M 5200 or Sikaflex 291 in. (Other adhesives can loosen after a short time).
Others are being scanned by road noise directly through the car's floor. Here you can remove mats and other things. and glue it up double with Acoustblok on the floor. When laying over some profiles you can soften the Acoustic block with a hot air gun. (Do not use this in steam from glue!)
Above this you put a thin mat before placing blankets or vinyl mats in place. You will now have significantly reduced direct noise and a good deal of vibration. You can also dress other parts of the car with sense and sense to better direct and airborne noise.
Acoustic block is waterproof, non-foam and UV resistant and will last forever except for mechanical wear. Also remember that in the engine room it is poor if the working temperature exceeds 120 gr. C.
Remember that many times the car - or parts of it is designed to be difficult to reach. Other places can overlook useful places to noise isolate - such as inside wheel well for spare wheel.
Noise isolation is a difficult and somewhat unpredictable job. You can - if lucky - be able to reduce the noise so much that you notice improvement, but the silence you want is difficult to reach.
Much depends on the thickness and pattern of the tires. Talk to the supplier about opportunities here. Especially electric cars are plagued by this as the highest noise source. When the engine trip is gone, they hear the wheel loop and the winch the better.