The Indian automobile industry is experiencing a significant shift, propelled by environmental necessities and national climate obligations set at the CoP26 summit, aiming for a 45% decrease in CO₂ emissions by 2030 and reaching carbon neutrality by 2070 [1]. Transportation continues to be a significant source of air pollution; consequently, India is enhancing its regulatory frameworks with BS VI Stage 2 regulations, CAFE Phase III norms set for 2027, and CAFE Phase IV by 2032 [2]. Furthermore, the transition from MIDC to WLTP driving cycle is meant to increase the accuracy of the efficiency and emissions assessments [2]. To comply to these upcoming regulations, the automotive industry is moving toward producing high efficiency engines in India. A naturally aspirated (NA) 1.5L, 4- cylinder inline gasoline engine was selected from Indian market for this study. Maximum Brake Thermal Efficiency (BTE) of this engine is around 35%. Assessment of new technologies were performed by implementing them stepwise to see the impact on BTE. A well calibrated 1D GT-SUITE model was considered from FEV database to perform the simulation-based approach to increase the BTE by improving the stroke/bore (s/B) ratio, increasing the compression ratio, implementing Atkinson cycle with variable valve timing (VVT) / variable valve lift (VVL) optimization, and charge motion refinement for optimal in-cylinder combustion. Low temperature cooled EGR (TEGR <70°C) and pre-catalyst pick-up distributed EGR strategies were simulated to improve the combustion stability and pumping loss for BTE improvement. Friction losses were further minimized by implementing the polished surfaces, electrification of auxiliary components, and other advanced surface treatments. Advanced technologies including Dual Port Fuel Injection (Dual PFI) system, high energy ignition system with thermal swing coatings, and system designed to operate with highly diluted mixture are required to achieve maximum BTE. These technologies would also be explored in this study. This paper also covers the rivals' restrictions put on engine geometry and number of cylinders concerning possible max. BTE level with which the engine can achieve. With the completed study, the efficiency step walk document indicated BTE improvement from each technology step to achieve a target max. BTE for the engine