MoRTH Introduces WLTP Emission Standards for M1, M2 Vehicles from April 2027

The Ministry of Road Transport and Highways has issued an amendment to the Central Motor Vehicles Rules, 1989 after releasing draft proposals earlier and reviewing objections and suggestions received from stakeholders.

Under the amendment, the requirements will apply to category M1 vehicles and to category M2 vehicles with a gross vehicle weight not exceeding 3,500 kg. The standards will cover models manufactured on or after 1 April 2027.

The notification prescribes emission limits for vehicles fitted with positive ignition and compression ignition internal combustion engines. The parameters include carbon monoxide, total hydrocarbons, non-methane hydrocarbons, nitrogen oxides, particulate matter and particle number. The tests for type approval will be conducted on a chassis dynamometer and will follow the procedures laid down in AIS-175, as amended from time to time.

The rules state that there will be no relaxation of norms for conformity of production. Manufacturers will be required to follow the compliance procedures defined in AIS-175 for demonstrating that vehicles continue to meet the prescribed limits.

For gasoline-fuelled vehicles, evaporative emissions must not exceed 2.0 grams per test. The crankcase ventilation system must also be designed in a way that prevents the release of gases into the atmosphere. Testing procedures will be as specified in AIS-175.

The amendment assigns deterioration factors for positive ignition engines and provides pathways for establishing these factors through whole-vehicle ageing or bench durability testing. Such tests are to be carried out in accordance with AIS-175 and must be conducted by agencies authorised under the rules.

Vehicles covered under the amendment will need to be equipped with on-board diagnostic systems capable of identifying malfunction areas when emissions rise above defined thresholds. The notification lists specific limits for pollutants such as carbon monoxide, non-methane hydrocarbons, nitrogen oxides and particulate matter. It also defines minimum in-use performance ratios for different monitoring systems, with detailed tracking requirements referenced to AIS-175.

For type approval, real-world driving emissions will be measured using portable emission measurement systems. Conformity factors, along with margins that account for measurement uncertainty, have been specified for nitrogen oxides and particle number. Carbon monoxide will also be measured and recorded during these tests.

The notification further states that vehicles running on CNG, Bio-CNG or HCNG will need to meet applicable safety requirements under the relevant AIS standards. Manufacturers will be required to declare compatibility with higher ethanol blends such as E85 and E100 and display this information through a visible label. In addition, all gasoline mono-fuel and bi-fuel vehicles, including hybrids, must be certified for operation on E20 fuel.