In India, fuel economy is one of the most critical factors influencing a customer's decision to own a passenger car. Beyond consumer preference, fuel consumption also plays a significant role in the nation's energy security. Inline of this, the government promotes fuel-efficient vehicles and technologies through various regulations, policies, and mandates. Vehicle manufacturers, in response, focus on designing vehicles that align with both customer expectations and regulatory requirements. Fuel economy certification is typically based on standardized laboratory tests that simulate controlled environmental conditions, driving cycle (MIDC), vehicle load, and operation of electrical and electronic systems. However, actual on-road driving conditions by end user vary significantly due to factors such as traffic conditions, ambient temperature, air conditioning use, driving behaviour and variable loading of the vehicle. With implementation of Bharat Stage VI, Real Driving Emission (RDE