Internal combustion engines have been there for nearly a century and half and will continue to remain and play a major role in the mobility industry. Exhaust aftertreatment system is like a sibling to the internal combustion engine, since both work in tandem, complementing each other's functions and contributing to the overall goal of reducing emissions and improving environmental sustainability. The faster adoption of Euro VI emission norms globally and announcement of Euro VII norms, emphasizes the need to continually improve our exhaust aftertreatment systems. This paper presents a breakthrough in the development of a C-shaped compact, modular and cost-effective exhaust aftertreatment system (EATS) with an auricle mixer, designed at Ashok Leyland. This system is specifically engineered to meet the stringent requirements of BS VI OBD-II emission norms for diesel engine applications and can be upgraded for H2 ICE. A typical BS VI EATS has catalysts, sensors and urea nozzle integrated in the canning and the overall efficiency of pollutants reduction depends on the system integration, with multiple interdependent factors. For NOx reduction, mixer also plays a key role in mixing and evaporation of the urea injected and also in ensuring uniform gas distribution. This paper explains the development of C-shaped EATS contributing to lower backpressure, lower thermal loss, better urea mixing, minimum child parts compared to existing EATS in the market, with ease of manufacturing and modular in design such that it can be packaged in minimum space, with minimum number of variants, across complete portfolio of M&HCV Trucks and Buses. In the conventional Box shaped EATS, there is a separate hydrolysis pipe for urea decomposition and mixing, leading to high thermal loss and complicated mounting system. In the C-shaped EATS, the integration of an auricle mixer, optimally placed within the system surrounded by exhaust gas flow, improves mixing of urea with the exhaust gas, resulting in reduced thermal loss and enhanced emission performance. Comprehensive evaluations of the C-shaped EATS demonstrated that the new architecture excelled in packaging space, weight, and performance parameters, surpassing the base system. The design achieves a harmonious balance between modularity and performance, providing a cost-effective solution for meeting the stringent performance and emission requirements.