The central government has admitted that E20 petrol can result in around three to five per cent reduction in mileage in some older vehicles which were designed for E10 fuel, but has said that extensive testing, as well as real-world experience, have not found any widespread damage being caused to the engines. There have also been no vehicle breakdowns that can be linked to the blending of ethanol in fuel, the government told Parliament on Wednesday.
Minister of State for Petroleum and Natural Gas Suresh Gopi, in written replies to questions raised in the Rajya Sabha, said fuel efficiency is dependent on a number of factors, including driving habits, maintenance of vehicles, tyre pressure, air-conditioning load, as well as wheel alignment.
"Any reduction in fuel economy in certain older E10-designed vehicles is generally marginal (around 3-5%)," the written reply revealed. It also said that E20 fuel provides higher octane, better anti-knock performance, improved combustion characteristics, and smoother acceleration.
According to the government, E15 petrol has been in use for more than 3.5 years, while E19 and E20 fuels have been in use for more than 2.5 years. It also said that upwards of 20 crore two-wheelers and 3 crore petrol-run cars, including older vehicles which were manufactured before the E20 certification, have been operating on these blends without any verified evidence of widespread engine failures linked to ethanol-blended fuel.
The government also said that manufacturer service data has revealed that a leading manufacturer of four-wheelers serviced 2.84 crore vehicles during FY 2025-26, including 1.5 crore older non-E20-certified vehicles, without reporting any vehicular damage attributable to E20 fuel. It also said that a manufacturer of two-wheelers has reported no higher incidences of damage in vehicles running on E20 fuel compared with earlier blends.
The government also said that vehicle manufacturers are still honouring warranty obligations for vehicles using E20 fuel that is compliant with specifications.
It also said that extensive laboratory studies and field trials have been carried out, but no significant variation has been found in legacy vehicles for parameters such as drivability, startability, metal compatibility and plastic compatibility.
There is no proposal to revert to E0 or E10 petrol, the government said, adding that maintaining parallel nationwide supply chains for E0, E10 and E20 across more than one lakh retail outlets would increase logistics complexity, inventory and handling costs.
ARAI testing backs E20 fuel rollout: Govt
The government also said that the Ethanol Blended Petrol (EBP) Programme was carried out in a phased, calibrated, scientifically validated and consultative approach, which involved the NITI Aayog, Oil Marketing Companies, automobile manufacturers, Automotive Research Association of India (ARAI), the Society of Indian Automobile Manufacturers (SIAM), the Indian Institute of Petroleum (IIP) and other technical institutions.
Gopi said that extensive laboratory studies, durability trials and field validation were carried out before E20 was introduced to the public. These tests covered engine durability, material compatibility, corrosion resistance, drivability, emissions, fuel economy and overall vehicle performance. He also said that E20-compliant vehicles get approval only after they undergo the prescribed homologation process and receive certification for sale after extensive tests.
The government, responding to concerns, said that studies conducted by ARAI, SIAM, IIP, Indian Oil Corporation Ltd (IOCL) and automobile manufacturers have found that E20 does not result in abnormal wear or tear in cars, and does not cause compatibility issues when used as per prescribed standards. The reply added that tests carried out by SIAM and ARAI have shown improvements in acceleration and ride quality, as well as reduced carbon emissions.
