Ballisitc and Bulletproof Standards for Armored Cars and Vehicles

Ballistics Specifications describe the attributes of a projectile which must be defeated by a particular material in order to comply with the various protection levels.
Ballistics Specifications do not specify a material.  Any material that can defeat the specified projectile will be rated according to that specification.  This is true if it is steel, composite, exotic or concrete.
Ballistics specifications are standardized in many countries and are used as reference when deciding on a protection level that will be required for a particular service requirement.  Once the protection level is determined, then materials used in the construction of the vehicle should all be compatible with that standard.
It is common for Armoring companies to create their own In-House standards for Ballistics.

Personal security is especially important in times as these with terrorist attacks everywhere. Not only politicians and VIPs protect themselves with armoured vehicles, but also private individuals in senior positions and that work for specific companies. In these cases personal safety within the vehicle is especially important,as theses are often consided 'soft targets' by attackers. By using the correct construction and armouring the risk can be reduced to a minimum.
Most armoured vehicles nowadays don't obviously look armoured, but they offer the highest possible sense of security for the owner.