With increasing road traffic and pollution, it becomes responsibility for all OEM to increase fuel efficiency and reduce carbon footprint. Most effective way to do so is to reduce weight of the vehicle and more use of ecofriendly recyclable material. With this objective we have come up with Light weight, cost effective sustainable design solution for Injection moulded RQT (Rear quarter trim). It is an interior plastic component mounted in the III row of the vehicle. This is required to ensure inside enhanced aesthetic look of the vehicle and comfort for 3rd row passengers. Conventionally RQT of vehicle with 3rd row seating is made using plastic material (PP TD 20). With the use of plastic moulded RQT there is a significant weight addition of around 6 kg per vehicle along with reduced cabin space, huge investment and development time impact. In PROJECT X model which is a 4.4 meter vehicle with 3rd row seating capacity, we have challenged the conventional way of design and have come up with “Light weight, cost effective sustainable design solution” of rear RQT, C pillar lower and D pillar lower with an objective to increase cabin space, reduce weight & investment by at least 50% without compromising the aesthetic appeal and HVAC performance of the vehicle. To achieve a unique solution towards conventional moulded RQT it was necessary to understand the various contributing factors towards design constraints, such as aesthetic requirement, part geometry, material options, industry standard, manufacturing constraints, interface requirement, cost, investment and most importantly the weight saving with a challenge to conventional way of design. In order to overcome all the above mentioned constraints rigorous detail study, data mining, benchmarking, engineering feasibility & brainstorming was performed. It was observed that most of the internal and external competitors with 3rd row passenger seat have conventional injection moulded RQT in passenger compartment. Appropriate design with correct reinforced configuration of fabric was considered leading to weight & per piece cost reduction by approx. 65% and investment cost reduction by approx. 50%. There were several other challenges in term of harmony with surrounding parts, fit & finish, CMF, ergonomic requirement and stringent timeline, which was resolved systematically. We have also followed First time right and every time right methodology to ensure defect free product and have demonstrated the same at initial stage through prototype validation at buck level as well as software level.