firewall.

About firewall

In automotive engineering, a firewall or bulkhead is the part of the automobile body that separates the engine compartment from the passenger compartment. It is most commonly a separate component of the body or, in monocoque construction, a separate steel pressing, but may be continuous with the floorpan, or its edges may form part of the door pillars. The inner and outer surfaces of the firewall are often coated with noise, vibration, and harshness (NVH) absorber to prevent most engine noise from reaching the passenger compartment. The name originates from steam-powered vehicles, where the firewall separated the driver from the fire heating the boiler.