A method of manufacturing a crash-resistant structural part for an automobile, the crash-resistant structural part including a beam element for receiving an impact force during a crash of the automobile is provided. The method comprises a step of arranging at least one layer of fibers having a length of 100 mm or more, and a step of mixing components required to form a thermoplastic polymer resin, the components including a reactive monomer, thereby forming a liquid precursor mixture of the thermoplastic polymer resin. At least one layer of fibers is impregnated with the liquid precursor mixture, and the beam element is formed by an in-situ polymerization reaction of the liquid precursor mixture having impregnated the at least one layer of fibers.