Thermoplastic elastomers belong to a class of materials that exhibit properties typical of rubbery materials, but have the combined physical properties of thermoplastics and elastomers and can be processed like thermoplastics. Styrene-ethylene-butylene-styrene (SEBS) thermoplastic elastomer is a regularly used elastomer in a wide variety of general-purpose rubber items, as well as in handlebar grips, toothbrushes, sports mouth guards etc. SEBS can improve the deformability and elastic mechanical properties of composites due to its long polymeric chains, which are joined into a network structure and have a high degree of mobility and flexibility. As of now, there are very few studies that have investigated the interaction between fly ash and other reinforcing agents such as long glass fibers in a polymer matrix. In a previous study by [PERSON] et al. [20], the effect of SEBS on the mechanical and thermal properties of polypropylene was investigated. The results showed an increase in toughness, expressed by an increase in energy at break and impact strength values, as well as an increase in elongation. Another study [21] investigated the effect of SEBS-halloysite masterbatch on the properties of hybrid polypropylene-glass fiber composites under optimal processing conditions. Improved hardness, modulus, tensile strength and impact strength were obtained for the polypropylene-chopped glass fiber composites containing masterbatches compared to pristine PP. A study by [PERSON] et al. [22] investigated the effect of SEBS on polypropylene composites filled with nanosilica particles, where the results showed a simultaneous increase in all tensile and impact characteristics in the case of the composite blend compared to neat PP. A similar investigation done by [PERSON] et al. [23] researched the properties of polypropylene-organoclay-SEBS nanocomposites and showed that the optimal ratio between SEBS and organosilicate in the polypropylene matrix can lead to improved toughness or stiffness for the nanocomposites and even a good balance between the two. These articles create a basis for the present study, as interactions between PP and SEBS or between PP and GF/nanofilers have already been studied. To our knowledge and compared to our previous articles, there have been no studies to investigate the interaction between fly ash powder, long glass fiber, and polymers containing a thermoplastic elastomer as an impact modifier. Therefore, the present study can lead to several potential research directions to develop various composites with specific applications in such areas as the automotive industry. Compared to our previous work, the novelty of this article consists in the use of polypropylene reinforced with long glass fibers, a specific type of ash and a thermoplastic elastomer and studying the interaction between the components and the effect of each on the properties of the final composite. The main purpose of our work was to analyze the characteristics of long glass fiber-reinforced polypropylene, elastomer and fly ash composites to indicate a cheaper but resourceful alternative for partial replacement of glass fiber and obtain new composites with a good balance of stiffness-toughness properties. Replacement of a percentage of glass fiber with fly ash and addition of thermoplastic elastomer will be monitored to determine if the ratio between components in the final compositions can provide similar or improved mechanical properties to commercial glass fiber-reinforced polypropylene composites commonly used in the automotive industry. This reduction in the glass fiber content must be accomplished without compromising the necessary properties of these composite materials for automotive applications.