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August 28, 2025 – India’s road transport minister Nitin Gadkari told Parliament on Thursday that blending 20% ethanol into petrol (E20) can cut vehicle fuel efficiency by 2% to 6%, depending on the vehicle’s category and age. In a written response to a parliamentary query, the Ministry of Road Transport and Highways added that tests – both on dynamometers and during on-road trials – found no evidence linking E20 to engine failures. The statement comes amid ongoing public backlash and political criticism over the early rollout of the ethanol blend, originally scheduled for 2030 but pushed forward to April 2025.
The efficiency drop means that a car running on E20 will travel fewer kilometers per liter of fuel compared to standard petrol, because ethanol contains about one-third less energy per unit volume than pure gasoline. Minister Gadkari emphasized that the reduction is within manageable limits and does not compromise vehicle operation. “More than 200 million two-wheelers and over 30 million petrol cars have operated on these blends without any verified evidence of widespread engine failure or vehicle breakdown attributable to ethanol blending,” he said.
A comprehensive study jointed conducted by the Automotive Research Association of India (ARAI), the Society of Indian Automobile Manufacturers (SIAM), and Indian Oil Corporation Limited (IOCL) evaluated the impact of E20 on BS-III, BS-IV, and BS-VI gasoline vehicles (both two-wheelers and four-wheelers). The tests followed standard certification procedures and custom protocols developed in consultation with original equipment manufacturers. The study found that E20 offers better acceleration, improved ride quality, and approximately 30% lower carbon emissions compared to E10 petrol. However, these benefits come at the cost of fuel economy.
Earlier this week, Gadkari informed lawmakers that BS-III vehicles manufactured between April 2005 and 2016 may need replacement of certain rubber parts and gaskets to run smoothly on E20. He framed this as a routine maintenance adaptation rather than a major overhaul. “The shift to E20 is part of India’s larger strategy to reduce dependence on volatile international crude oil prices and shield the economy from exchange rate fluctuations,” he added.
The policy’s premature rollout has drawn sharp criticism from opposition parties and consumer groups. They argue that older vehicles are not optimized for E20, leading to reduced fuel efficiency, higher running costs, and potential long-term damage to fuel systems. The Wire has reported complaints of “unusual wear and tear in engines, fuel tanks, carburetors and fuel lines” since implementation began last month. A digital protest group called “E20 Janta Party” has also mocked the government over poor road conditions and the forced adoption of ethanol-blended fuel.
To provide an independent perspective, the Society of Automotive Engineers (SAE) in the United States has noted that ethanol blends above 10% generally require engine recalibration to maintain efficiency. In the US, E15 (15% ethanol) is widely used in flex-fuel vehicles, but E20 remains rare outside specialized applications. “India’s move to E20 across all vehicles without a dedicated flex-fuel fleet is bold, but it carries risks. The efficiency drop may be higher than 6% in older engines that aren’t calibrated for higher ethanol content,” said Dr. Sarah Chen, a fuels researcher at the University of Michigan. She added that the long-term impact on fuel injectors, intake valves, and crankcase ventilation systems is still not fully understood.
The Indian government has not yet disclosed how many of the country’s 250 million petrol vehicles are fully compatible with E20. Meanwhile, the price of E20 petrol remains the same as E10 petrol at the pump, a point of contention for motorists who now pay the same for lower energy content.
As India pushes ahead with its ethanol blending roadmap – targeting 20% blending by 2025, five years ahead of the original target – the debate over fuel efficiency, engine durability, and consumer costs is likely to intensify. The ministry assures that continued monitoring will help refine the policy, while automakers are urged to accelerate engine optimization for E20 compatibility.
