Due to the increasingly stringent environmental requirements facing the automotive industry, modern research needs to be directed toward, apart from innovations in engine design, fuel improvement and combustion, the development of new low-mass structural elements with targeted mechanical properties for in-car applications. Composite and nanocomposite materials are increasingly being used for the purpose of making „lighter“ auto parts. If materials of better mechanical properties are obtained by the preparation of composites and nanocomposites, the car part can be produced thinner or lighter, which ultimately leads to a reduction in car mass and fuel consumption, as well as the emission of carbon (IV) oxide (CO2) into the atmosphere. Research on the preparation of nanocomposites with a polymer matrix for use in the automotive industry have been reported in the literature, while relatively few studies are available for metal-matrix nanocomposites and almost no data is available for the High Pressure Die Casting (HPDC) process of nanocomposite preparation. In this doctoral thesis, nanocomposite materials based on AlSi9Cu3 (Fe) Aluminium alloy and Multi-Walled Carbon Nanotubes (MWCNTs) were prepared by High Pressure Die Casting. The 0.05, 0.1 and 0.2 mas.% of nanofillers were added to the melt at two different positions within the high-pressure casting unit, in the pre-piston chamber and at the beginning of the tool, and in one experiment the matrix was changed by adding a Magnesium alloying element with adding nanofillers by mixing them in the melt. The chemical composition of the matrix was investigated with an optical emission spectrometer, the distribution and thermal stability of the nanofillers in the matrix after HPDC were investigated, as well as their influence on the microstructure by light microscopy and electron microscopy with energy dispersion, mechanical tests were carried out on a universal testing machine and Vickers hardness was determined. In all nanocomposite materials thermal degradation of the nanofillers did not occurre, and the best homogeneity was achieved in the samples with 0.05% MWCNT and Magnesium. The new materials obtained by adding nanofillers to the chamber showed better mechanical properties (increase in tensile strength of 16.5% and ductility of 49.7%) over pure alloy.