There are several types of materials used for soundproofing in cars:

1. Sound Absorbing Mats: These thick mats are often applied to the floor of the car and can absorb sound and vibrations.
2. Foam rubber panels: These lightweight panels are often used in doors and other interior spaces to dampen sound.
3. Heavy Barriers: These materials are heavier and are used to block out sound, often applied to car floors and firewalls.
4. Foam-like Materials: Flexible and lightweight, these materials are often used to seal small spaces and reduce sound leakage.

Tips for effective soundproofing

1. Clean Surfaces Thoroughly: For the soundproofing material to adhere properly, it is important that the surfaces are clean. Use alcohol-based cleaners for best results.
2. Use the right tools: Special tools to squeeze out air bubbles and ensure the material adheres properly can improve results.
3. Focus on Critical Areas: Doors, floors, wheel arches and hoods are areas where soundproofing can make the biggest difference.
4. Install Multiple Layers: In some cases, it can be effective to use multiple layers of sound insulation to maximize attenuation.
5. Check the fit: Make sure that the insulation material fits perfectly and covers all necessary surfaces without leaving gaps.