Composites have dramatically higher specific energy absorption than steel or aluminum. Composite-based crush cones and similar structures built into autobodies can absorb 120 kJ/kg, even up to 240, vs. about 20 for steel. Crush properties and costs can also be optimized by mixing costlier carbon fiber with lower-cost materials like fiberglass.
G. C Jacob et al. 2002. “Energy absorption in polymer composites for automotive crashworthiness.” Journal of Composite Materials 36, no. 7: 813. link