text: The primary functions of metallic foams in vehicles are to increase sound damping, reduce weight, increase energy absorption in case of crashes, and (in military applications) to combat the concussive force of IEDs. As an example, foam filled tubes could be used as anti-intrusion bars.  Because of their low density (0.4–0.9 g/cm), aluminium and aluminium alloy foams are under particular consideration. These foams are stiff, fire resistant, nontoxic, recyclable, energy absorbent, less thermally conductive, less magnetically permeable, and more efficiently sound dampening, especially when compared to hollow parts. Metallic foams in hollow car parts decrease weakness points usually associated with car crashes and vibration. These foams are inexpensive to cast with powder metallurgy, compared to casting other hollow parts.
  Compared to polymer foams in vehicles, metallic foams are stiffer, stronger, more energy absorbent, and resistant to fire and the weather adversities of UV light, humidity, and temperature variation. However, they are heavier, more expensive, and non-insulating.
  Metal foam technology has been applied to automotive exhaust gas. Compared to traditional catalytic converters that use cordierite ceramic as substrate, metal foam substrate offers better heat transfer and exhibits excellent mass-transport properties (high turbulence) and may reduce the quantity of platinum catalyst required.