The most important advantage composite materials have over other materials is their strength and rigidity combined with their light weight. Unlike metal, composites can be calibrated to exacting performance characteristics. When precisely calibrated the tensile strength and stiffness of composite materials can be as much as 2.5x greater than steel. This strength limits how much a structure will deform under load, therefore enabling it to handle higher loads before breaking.
Along with enhanced tensile strength, in certain conditions a composite part can be 5X lighter than steel. This lower weight can translate into higher fuel efficiency in transportation vehicles and reduce wear on associated parts.