The Ministry of Road Transport and Highways notified amendments to the Central Motor Vehicles Rules, 1989 on 23 October 2026 to permit E85 and E100 fuels in certified flex fuel vehicles. The reform builds on India’s E20 petrol programme which reached 20 percent ethanol blending in 2025-26. It gives makers a legal path to certify vehicles that can run on any blend from E20 to pure ethanol.
What Are E100, E85 and Other Approved Fuels?
In fuel names, the letter E stands for ethanol and the number shows the share of ethanol in volume. E20 petrol is petrol blended with 20 percent ethanol. E85 fuel contains up to 85 percent ethanol and about 15 percent petrol. E100 fuel consists almost entirely of ethanol, in practice 93 to 95 percent ethanol mixed with a small share of petrol and additives that help in cold starts and give the flame a visible colour.
Ethanol is an alcohol made by fermenting sugars and starches. In India it is mainly produced from sugarcane juice, B-heavy molasses and C-heavy molasses, and from grains such as maize, broken rice and surplus food grains. It can also be made from farm waste such as straw and bagasse through second generation technology. The Pradhan Mantri JI-VAN Yojana, launched to support advanced biofuel plants using crop residue and other renewable feedstock, backs this shift away from food based feedstock.
The amendment also updates two other alternative fuels. B100 biodiesel is fuel made of 100 percent biodiesel, which is chemically treated vegetable oil or animal fat that meets the IS 15607 standard. It is meant for diesel engines in trucks, buses and tractors. HCNG stands for Hydrogen-enriched Compressed Natural Gas, a mix of hydrogen and CNG with about 18 to 20 percent hydrogen by volume. HCNG burns faster and cleaner than plain CNG and can use existing CNG stations, so it is seen as a first step toward hydrogen use in buses and heavy vehicles.
| Fuel | What it contains | Where it is used |
|---|---|---|
| E20 | 20 percent ethanol, 80 percent petrol | All new petrol vehicles sold after April 2023 and April 2025 tuning norms |
| E85 | Up to 85 percent ethanol, rest petrol | Only certified flex fuel vehicles |
| E100 | 93 to 95 percent ethanol, rest petrol and additives | Only certified flex fuel vehicles |
| B100 | 100 percent biodiesel | Diesel engines in trucks, buses, tractors |
| HCNG | About 18 to 20 percent hydrogen mixed with CNG | Buses and heavy duty gas engines |
What Is a Flex Fuel Vehicle and How Does It Work?
A flex fuel vehicle (FFV) is a vehicle with a petrol engine designed to run on more than one fuel blend. It has one fuel tank and can use petrol, E20, E85 or E100 within the range approved by the maker. The driver does not turn any switch. The vehicle senses the blend and adjusts itself.
An ordinary E20 compliant car cannot do this. Its pipes, seals and engine settings are built to tolerate only up to 20 percent ethanol. Putting E85 or E100 in such a car can cause lean running, corrosion of rubber and metal parts, and engine damage over time. That is why the ministry has stated clearly that E85 or E100 shall be used only in vehicles designed by Original Equipment Manufacturers (OEMs) as flex fuel vehicles.
A flex fuel engine differs in linked parts that work together. It has an ethanol content sensor in the fuel line. The sensor measures the ethanol share from the fuel properties or from exhaust readings and sends the data to the Engine Control Module (ECM). The module then changes the amount of fuel injected and the timing of the spark. The engine also uses a high flow fuel pump and larger injectors. Ethanol holds about one third less energy per litre than petrol, so the engine must spray 30 to 40 percent more fuel to make the same power. All parts that touch fuel use ethanol proof materials such as special rubber seals, stainless steel rails and coated tanks, because ethanol absorbs water and attacks soft metals and ordinary plastics.
Ethanol also has a benefit. Its octane rating is very high, around 100 to 105 for E85, so it resists knock. Knock is early and uncontrolled burning that can harm the engine. A flex fuel engine can advance the spark timing on high ethanol blends to gain efficiency and power. The trade off is mileage. A car will cover a shorter distance on a litre of E85 or E100 than on a litre of petrol, though the final running cost depends on fuel prices.
Yes, a certified flex fuel car can also run on pure petrol or on E20. The sensor simply detects the low ethanol share and the computer uses petrol settings. In India, makers including Maruti Suzuki and Toyota Kirloskar Motor have shown E85 and E100 prototypes. Maruti Suzuki launched a WagonR flex fuel prototype certified for E85 but capable of running from E20 to E100. The new rules now let such models complete type approval for E100 as well.
What the Amendment Changes in Rule 115
The Central Motor Vehicles (Amendment) Rules, 2026 were notified on 23 October 2026 as G.S.R. 911(E). They were issued under Section 110 of the Motor Vehicles Act, 1988, which gives the central government power to make vehicle construction and emission rules. A draft had been published on 27 April 2026 for public objections. The final rules came into force on publication in the Official Gazette.
The core change sits in Rule 115 of the Central Motor Vehicles Rules, 1989, which sets emission standards and fuel related test conditions. References to E85 in five emission tables have been replaced with E85 or E100. This places pure ethanol inside the type approval system alongside E85. A new explanatory note states that E85 or E100 shall be used only in vehicles designed by original equipment manufacturers as flex fuel vehicles.
The notification makes other updates in the same tables. The reference to B10 biodiesel in one table has been changed to B100, which opens certification for vehicles running on pure biodiesel. Petrol is now shown as gasoline E10 or E20 instead of only E10, which reflects the nationwide shift to E20. The description of HCNG has been corrected from Hydrogen plus CN to Hydrogen plus CNG. For heavy duty vehicles, the tables now cover B100 and HCNG combinations alongside diesel, CNG, LNG and hydrogen.
The ministry added that testing for flex fuel models will be done on both petrol and E85 or E100 for exhaust pollutants and onboard diagnostics. Crankcase, evaporative and durability tests remain on petrol alone for lighter vehicles. Minor printing errors were also fixed, including the change of Annexure S to Annexure SA for E100 test procedure and corrections to chemical symbols and units.
Gross Vehicle Weight Limit Raised From 3000 kg to 3500 kg
Gross Vehicle Weight (GVW) means the maximum permitted weight of a vehicle when fully loaded. It includes the weight of the vehicle, passengers, cargo and fuel. It is different from unladen weight, which is the weight of the empty vehicle alone.
Rule 115 had applied one set of light vehicle emission tables to petrol and diesel vehicles with gross weight not exceeding 3000 kg. The amendment raises this cut off to 3500 kg. This aligns India with the global practice where 3.5 tonnes marks the boundary between light and heavy vehicles. The M1 category for passenger cars is also defined around the same 3500 kg limit.
In practice, more vans, pickups and small trucks will now fall under the light vehicle test procedure. The change simplifies certification for makers and brings a wider set of models under the same pollutant limits and test cycles as cars.
Why India Is Pushing Ethanol Blending Beyond E20 Petrol
India imports about 85 to 88 percent of its crude oil. Every rise in global prices widens the import bill. The Ethanol Blended Petrol (EBP) Programme, started as a pilot in 2001 and launched formally in 2003, was designed to cut this dependence with home grown fuel. The National Policy on Biofuels, 2018, amended in 2022, first set a target of 20 percent blending by 2030. The target was later advanced to Ethanol Supply Year 2025-26.
India met the E20 target five years early. Average blending rose from less than 1.5 percent in 2013-14 to 20 percent in 2025-26. Ethanol procurement by oil marketing companies rose from about 38 crore litres to more than 1200 crore litres in the same period. Production capacity grew from 421 crore litres in 2014 to about 2000 crore litres in 2026. The petroleum ministry reports foreign exchange savings of more than ₹1.97 lakh crore since 2014-15, substitution of about 31.6 million tonnes of crude oil, and payments of more than ₹1.66 lakh crore to farmers and distilleries.
The ministry links higher blends to cleaner air, rural jobs and climate goals. Ethanol has a lower fossil carbon footprint than petrol. High blends cut tailpipe carbon monoxide and some hydrocarbons. When made from waste or efficient feedstock, they also lower lifecycle greenhouse gas emissions. The government presents flex fuel technology as support for Atmanirbhar Bharat and the goal of net zero emissions by 2070. Brazil and the United States already run large flex fuel fleets, which shows the technology is mature.
Concerns remain. Owners of older cars designed for E10 have reported lower mileage on E20. Ethanol holds less energy, so fuel efficiency falls slightly. The government accepts a small drop in such cars but says there is no verified evidence of wide engine damage from E20 in compliant vehicles. Questions have also been raised about diverting sugar, maize and rice to fuel and about water use, since sugarcane and paddy together use about 70 percent of irrigation water. The push for second generation ethanol from straw, bagasse and bamboo aims to ease this pressure.
The new amendment does not force a change for current owners. The ministry has clarified that compatibility with E10 or E20 does not mean suitability for E85. No existing owner must switch fuels or modify a vehicle now or in future. Motorists should check the fuel compatibility sticker and follow the owner manual. Petroleum Minister Hardeep Singh Puri has also stated there is no plan to raise the general petrol pool beyond E20. E85 and E100 will be sold as separate options only for certified flex fuel vehicles.
| Feature | E20 vehicles | Flex fuel vehicles |
|---|---|---|
| Fuels allowed | Petrol and up to 20 percent ethanol | E20 to E85 or E100, including petrol |
| Engine and fuel system | Hardened for up to 20 percent ethanol | Larger injectors, ethanol proof parts, blend sensor, special engine maps |
| Mileage effect | Small drop in older E10 designs | Larger drop on E85 or E100 per litre, offset by price and octane gains |
| Who must act | No change needed | Only buyers who choose a certified flex fuel model use high blends |
Key Takeaways
- The Central Motor Vehicles (Amendment) Rules, 2026 were notified on 23 October 2026 under Section 110 of the Motor Vehicles Act, 1988 to include E100 alongside E85.
- E85 holds up to 85 percent ethanol and E100 holds 93 to 95 percent ethanol, and both can be used only in OEM certified flex fuel vehicles.
- The rules expand certification for B100 biodiesel and HCNG combinations for trucks, buses and heavy duty vehicles.
- The Gross Vehicle Weight limit for light petrol and diesel emission tests was raised from 3000 kg to 3500 kg.
- India achieved 20 percent ethanol blending in 2025-26, five years early, with procurement rising from 38 crore litres in 2013-14 to over 1200 crore litres.
