In a significant move towards transparency and more realistic fuel efficiency figures, the Ministry of Road Transport has proposed mandatory testing of car mileage with the air conditioning (AC) system turned on. This regulation will apply to all cars, including those with internal combustion engines (ICE) and electric vehicles (EVs), manufactured or imported in India from October 1, 2026.

Currently, car manufacturers in India declare fuel efficiency based on tests conducted without the AC running, a practice aligned with European norms. However, government officials have noted that these figures often don't reflect actual on-road performance, leading to a discrepancy between claimed and real-world mileage. The new rule aims to bridge this gap by providing consumers with a more accurate representation of fuel consumption under typical driving conditions, where AC usage significantly impacts mileage and energy consumption.

Following the implementation of the new testing procedure, car manufacturers and importers will be required to include mileage figures for both AC-on and AC-off conditions in the vehicle's user manual and on their websites. This will empower consumers to make better-informed purchasing decisions based on realistic mileage expectations.

The testing procedure will adhere to Automotive Industry Standard (AIS) 213, which outlines detailed methods for measuring vehicle emissions and fuel consumption while the AC system is operational. This standard is designed to capture the additional fuel consumption and emissions generated by the AC load, which can substantially affect real-world efficiency and pollution levels.

The impact of AC usage on fuel consumption is well-documented. Tests show that running the AC can significantly reduce the range of plug-in hybrid electric vehicles (PHEV) in hot environments. Designing for air conditioning electrical loads also affects the energy storage system size and cost for PHEVs and EVs. Even in conventional vehicles, the AC compressor, which is powered by the engine, consumes energy and reduces mileage.

While the regulation mandates testing with the AC on, the specifics of the testing conditions, such as temperature settings and fan speed, will likely be standardized to ensure consistent and comparable results across different models. The goal is to simulate typical usage scenarios.

This initiative is part of a broader effort to increase consumer awareness about vehicle emissions. In the near future, car owners may receive detailed information about vehicle emissions. By mandating AC-on mileage testing, the government is taking a significant step towards providing consumers with more transparent and reliable information about vehicle fuel efficiency, enabling them to make informed choices that align with their driving needs and environmental concerns.