The Ministry of Road Transport and Highways (MoRTH) has notified amendments to the Central Motor Vehicles Rules (CMVR), 1989, establishing emission and testing requirements for vehicles designed to run on ethanol-petrol blends containing up to 100% ethanol (E100) and pure biodiesel (B100).

The notification, dated October 23rd, finalises the homologation framework for these vehicles, providing original equipment manufacturers (OEMs) with a regulatory pathway to transition from prototype development to production.

The amendments cover fuel specifications, vehicle classification thresholds and technical references used in emission-related tables and testing provisions. They also expand the regulatory framework for higher ethanol blends and alternative fuels, following earlier proposals that included E85, E100, B100 biodiesel and hydrogen-CNG combinations.

E100 requirements for flex-fuel vehicles

An amendment to Rule 115 replaces the existing E85 fuel parameters in the relevant emission tables with provisions covering E85 or E100. An explanatory note clarifies that these fuels may be used only in flex-fuel vehicles (FFVs) specifically designed and certified by OEMs for this purpose.

A senior MoRTH official stated that fuels containing more than 20% ethanol and up to 100% ethanol are intended exclusively for vehicles designed and certified to use them. Vehicles approved for E20 or conventional petrol cannot use E85 or E100 unless they have the required compatibility and certification.

The amendments also standardise the classification of petrol blends as E10 and E20, aligning emission testing protocols with the fuels available at retail outlets. E85 comprises 85% ethanol and 15% petrol, while E100 consists of nearly pure ethanol. Flex-fuel vehicles are designed to operate on higher ethanol concentrations than conventional petrol vehicles.

India achieved its 20% ethanol-blending target in 2025, five years ahead of the original deadline of 2030 established under the National Policy on Biofuels. Since April 1st, 2026, E20 has been the mandatory standard petrol available at regular fuel pumps nationwide, effectively phasing out unblended petrol and E10 blends.

Automakers have been manufacturing vehicles with materials compatible with E20 fuel since April 2023. However, the transition has raised concerns among owners of older vehicles that are not compatible with E20. The formal classification of E10 and E20 in the regulations is intended to ensure that emission testing requirements correspond with the fuel blends currently available.

The government is promoting ethanol-blended petrol as part of its strategy to reduce dependence on imported crude oil, which contributes to India's current account deficit. Flex-fuel vehicles have also gained relevance amid the conflict in West Asia, which has left several countries, including India, vulnerable to energy supply disruptions.

In June 2026, Maruti Suzuki India launched the Wagon R Flex Fuel, described as India's first flex-fuel passenger vehicle. The model can operate on ethanol-petrol blends ranging from E20 to E100. Following the introduction of E85 at select Indian Oil Corporation (IOCL) retail outlets in mid-2026, the amended rules provide passenger vehicle manufacturers, including Maruti Suzuki and Toyota, as well as two-wheeler manufacturers, with a defined homologation pathway for the commercialisation of their flex-fuel prototypes.

Toyota Motor Corporation, Tata Motors and Hyundai Motor Company are also developing flex-fuel vehicles for the Indian market as policymakers seek to reduce the country's fossil fuel import bill.

Revised weight threshold for emission testing

The government has increased the gross vehicle weight (GVW) threshold for testing from 3,000 kg to 3,500 kg for the light petrol and diesel vehicles covered by the amendments.

This allows vehicles weighing between 3,000 kg and 3,500 kg to undergo emission testing using standard chassis dynamometer drive-cycle limits rather than heavy-duty engine dynamometer testing, which generally applies to vehicles weighing more than 3,500 kg. The revision affects the testing framework for vehicles in the light commercial vehicle and SUV segments that fall within the revised weight range.

B100 biodiesel framework for commercial vehicles

The amendments also establish a regulatory pathway for vehicles using B100, or pure biodiesel, by replacing B10 with B100 in the relevant testing parameters. This provides a basis for homologating vehicles designed to run on pure biodiesel, particularly in the commercial vehicle and construction equipment sectors.

However, the adoption of B100 in heavy transport faces constraints, including limited feedstock availability and higher production costs compared with conventional diesel. Although the testing protocol for pure biodiesel has been established, OEMs are expected to focus initially on B20-compatible platforms before expanding the use of B100 through dedicated pilot operations. Most global and Indian heavy-duty diesel engines are validated to use blends containing up to 20% biodiesel (B20) without major fuel-system modifications.

Vehicles running on B100 require dedicated fuel pre-heaters, specialised elastomers and shorter maintenance intervals because of the risks of fuel oxidation and gelling at lower temperatures.

Implications for component manufacturers

With the regulatory requirements established, attention is expected to shift to the Tier-1 supply chain. Component manufacturers will need to expand domestic production of ethanol-compatible fuel lines, specialised combustion sensors and corrosion-resistant engine components to support OEMs planning to introduce flex-fuel vehicles.

The amendments establish a certification framework for higher ethanol blends and pure biodiesel. However, wider adoption will depend on vehicle compatibility, fuel availability, production costs and the readiness of supporting components and infrastructure.