This project report summarizes a study of petrol and diesel engines manufactured by Maruti Suzuki. It examines different types of engines used, as well as common problems that occur under running conditions. The report provides a thorough analysis of VVT and DDiS engines, evaluating their usefulness, efficiency, and high performance enabled by new technologies. It also includes case studies of specific engine issues. The goal is to gain understanding of modern engine designs and typical maintenance concerns.