Vehicle owners have recently raised concerns related to a potential “drastic” drop in mileage and about the long-term health of engines due to the use of E20 fuel.
12 Aug 2025 | 11189 Views | By Kiran Murali
As India pushes ahead with its ambitious ethanol-blending programme, the rollout of petrol with 20% ethanol (E20) has sparked concerns among consumers, especially those with older vehicles. Amid fears and reports of “drastic” mileage to concerns over engine wear, corrosion, and warranties, the government has issued a clarification stating that ...
This is an Autocar Pro Plus article. Subscribe to continue reading.
As India pushes ahead with its ambitious ethanol-blending programme, the rollout of petrol with 20% ethanol (E20) has sparked concerns among consumers, especially those with older vehicles. Amid fears and reports of “drastic” mileage to concerns over engine wear, corrosion, and warranties, the government has issued a clarification stating that any claims of drastic reduction in efficiency are “misplaced” and any decrease in mileage in older vehicles running on E20 fuel has been "marginal, if at all."
“Extensive discussions have been carried out with the Society of Indian Automobile Manufacturers (SIAM) as well as prominent manufacturers of vehicles. The efficiency drop (if any) in E10 vehicles has been marginal. For some manufacturers, vehicles have been E20 compatible from as far back as 2009. The question of any drop in fuel efficiency in such vehicles does not arise,” the Ministry of Petroleum and Natural Gas said on Tuesday.
The clarification tries to address potential risks associated with the use of E20 petrol. Many drivers, particularly those with older vehicles, fear that using a fuel with more than 10% ethanol could harm their engines. Apprehensions include a negative impact on fuel economy, a shortened engine lifespan, and the possibility of expensive repair costs. The government believes that the benefits of E20, such as lower emissions, reduction of crude oil imports and rural support, far outweigh the minor challenges related to fuel efficiency or any impact on the vehicles, which can be managed through routine maintenance.
The government noted that concerns related to performance and mileage that are being raised now were anticipated earlier itself, and an Inter-Ministerial Committee of the NITI Aayog has “examined them at length.” The government also added that Indian Oil Corporation, Automotive Research Association of India (ARAI) and Society of Indian Automobile Manufacturers (SIAM) carried out research on this mileage issue and it backs their stand.
“The critiques suggesting that E20 causes a “drastic” reduction in fuel efficiency are misplaced. Vehicle mileage is influenced by a variety of factors beyond just fuel type. These include driving habits, maintenance practices such as oil changes and air filter cleanliness, tyre pressure and alignment, and even air conditioning load,” the ministry said.
For older vehicles that were designed for E10, a marginal drop is expected. For example, a car with 110 horsepower might see a negligible reduction to 108 horsepower, and a vehicle that gets 15 kmpl could see that drop slightly to 14.7 kmpl. These changes are considered minor and likely won't be noticeable during normal driving conditions.
“Marginal drop in efficiency can be further minimized through improved engine tuning and use of E20-compatible materials, which leading automobile manufacturers have already adopted,” the ministry said.
The government also highlighted key benefits of using E20 fuel such as better acceleration, better ride quality and lower carbon emissions as compared to E10 fuel.
“Ethanol’s higher-octane number (~108.5 compared to petrol’s 84.4) makes Ethanol-blended fuels a valuable alternative for higher-octane requirements that is crucial for modern high-compression engines. Vehicles tuned for E20 deliver better acceleration which is a very important factor in city driving conditions. Additionally, Ethanol’s higher heat of vaporization reduces intake manifold temperatures, increasing air-fuel mixture density and boosting volumetric efficiency,” the government said.
Previously, petrol sold in India came with a Research Octane Number (RON) of 88. To meet stricter BS-VI emission standards, which aim to curb harmful pollutants, the RON was increased to 91 and now with the introduction of the E20, the octane number has been further boosted to 95, which the government says results in better anti-knocking properties and enhanced engine performance.
Concerns Around Vehicle Damage
Some consumers have highlighted that the fuel requirements for some older vehicles explicitly prohibit the use of petrol with an ethanol blend exceeding 10%. This has led to worries that potential vehicle damage and performance issues from the use of E20 fuel may not be covered under the manufacturer's warranty.
For instance, the user manual of Grand i10 Nios manufactured between 2019 and August 2023 says: “Do not use gasohol [a mixture of petrol and ethanol] containing more than 10 per cent ethanol, and do not use petrol or gasohol containing any methanol. Either of these fuels may cause driveability problems and damage to the fuel system, engine control system and emission control system.”
The manual also said that vehicle damage or driveability problems may not be covered by the manufacturer’s warranty if they result from the use of gasohol containing more than 10% ethanol. However, the government highlighted that there is no impact on the validity of the insurance of vehicles due to the usage of E20 fuel.
“Ethanol blending is a national programme. Some seek to derail it by fomenting fear and confusion in the minds of car owners by selectively picking information and creating a false narrative that insurance companies will not cover car damage due to the use of E20 fuels. This fear-mongering is totally baseless and has been clarified by an insurance company whose tweet screenshot was deliberately misinterpreted to create fear and confusion,” the government said.
While newer vehicles, especially those sold since 2023, are designed to be compatible with E20 fuel, older cars may face minor challenges in the long term. Their engines were not specifically tuned for this higher ethanol blend, potentially putting them at a disadvantage over time. However, a few industry experts say any concerns of corrosion are limited to a small percentage of cars and are only likely to become an issue after many years of use.
“For a vehicle owner who believes that his/her vehicle may require further tuning or parts replacement, the entire network of authorized service stations is available to respond to such requests,” the government said.
At an event organised by SIAM on Monday, Rajnath Ram, Adviser (Energy) at NITI Aayog, said that Indian vehicles have shown no abnormal wear and tear from using E20 fuel, even after driving up to 100,000 kilometers.
Some auto industry executives said the move to E20 fuel has raised concerns about the potential for corrosion in older vehicles. Ethanol's ability to absorb moisture can, over time, cause rust in metal components like fuel lines, tanks, and feeders.
However, they noted that even before the introduction of E10 fuel, the majority of Indian automakers had already started using corrosion-resistant materials like plastic fuel tanks and galvanized iron fuel lines. This means that the majority of the vehicles on the road today are already equipped to handle the higher ethanol blend.
The small portion of older vehicles, those with uncoated metal fuel systems, are the most susceptible to this issue. “For these cars, corrosion issues may begin to appear after a prolonged period of use, typically 8-10 years,” he said.
The government noted that in the case of certain older vehicles, some rubber parts and gaskets may need to be replaced slightly earlier than if non-blended fuel were used. However, this is an inexpensive replacement that can be easily handled during routine servicing. It is typically required only once during the vehicle’s lifetime and can be carried out quickly at any authorized workshop.
“Safety standards for E20, including corrosion inhibitors and compatible fuel system materials, are well established through BIS specifications and Automotive Industry Standards. Replacement of some rubber parts/ gaskets could be advised in certain older vehicles after prolonged use of say 20,000 to 30,000 kms. This replacement is inexpensive and easily done during regular servicing of the vehicle,” the ministry said in a social media post.
The ministry also highlighted that testing by major research bodies like the ARAI, the Indian Institute of Petroleum (IIP), and Indian Oil has confirmed that E20 fuel is safe for older vehicles. These tests showed that even legacy vehicles had "no significant variations, performance issues or abnormal wear-and-tear" when running on the new blend. The ministry added that E20 also passed crucial hot and cold startability tests without any engine damage.