E20 Fuel in India: What is its impact on vehicles and why is it not cheaper than petrol? | Explained
A joint study by Indian Oil Corporation (IOCL), the Indian Institute of Petroleum (IIP), the Society of Indian Automobile Manufacturers (SIAM) and the Automotive Research
A joint study by Indian Oil Corporation (IOCL), the Indian Institute of Petroleum (IIP), the Society of Indian Automobile Manufacturers (SIAM) and the Automotive Research Association of India (ARAI) found that E20 fuel does not require engine modifications for cars or two-wheelers, according to the government. What do government-backed studies say about E20’s impact on vehicles and mileage? Citing the study in the Parliament, which has not been made public, the government said legacy vehicles (i.e., vehicles manufactured before 2023, when E20-compatible vehicles began to be rolled out of factories) did not show any significant deterioration in performance, abnormal wear and tear, or issues relating to drivability, startability, or compatibility with metal and plastic components when operated on E20. The only exception identified was some BS-III vehicles introduced from April 1, 2005, and manufactured before 2016, where certain rubber parts and gaskets may require replacement during routine servicing. However, a news report on the findings of the above study highlighted that prolonged use of E20 in vehicles designed for E10 could lead to deterioration of hoses, gaskets, seals and O-rings, which may require replacement over time. During engine durability testing lasting 400-806 hours, a BS-VI turbocharged engine reportedly developed issues after about 265 hours of testing, indicating that some engine configurations may require closer evaluation. On fuel economy, automobile manufacturers have stated that E20 may result in a 3-5% reduction in mileage because ethanol has a lower energy content than petrol. However, the government says that overall fuel efficiency is influenced by several factors beyond fuel type, including driving habits, tyre pressure and alignment, vehicle maintenance, engine oil and air-filter condition, and air-conditioning use.
Real-world experience of drivers and mechanics since E20 rollout Many motorists and mechanics say that they have seen an increase in fuel-system-related problems since E20 became the default petrol across India in April 2025. Although these observations are anecdotal and do not establish that E20 is the cause, drivers have reported a noticeable drop in fuel efficiency, vehicles jerking while driving, engine misfires, and in some cases, stalling. Mechanics say the most common issues they are encountering include clogged fuel injectors, blocked fuel filters, excessive carbon deposits in injectors and carburettors of older vehicles, oxygen (O₂) sensor failures, and fuel pump failures. They also report sharply higher repair costs, with routine fuel-system repairs that previously cost ₹3,000-₹4,000 now running into ₹12,000-₹15,000. Severe cases involving engine damage can cost substantially more. Experts caution that similar symptoms can also arise from ageing vehicles, inadequate maintenance, or contaminated fuel, and they say these factors must be evaluated before attributing problems solely to E20. Experts on E20’s impact on vehicles manufactured after 2023 Experts say that the concerns associated with E20 are largely confined to older vehicles that were not designed or calibrated for higher ethanol blends. Vehicles manufactured from 2023 onwards that have been certified as E20-compatible have been specifically engineered to run on the fuel. According to automobile consultant and former Executive Director at Ford India, Vinay Piparsania, manufacturers of E20-compliant vehicle review the entire fuel system, including fuel pumps, injectors, seals, hoses, pipes and metallic components, to ensure long-term compatibility with E20. The engine management software is also recalibrated to maintain the correct air-fuel mixture, performance, emissions and cold-start behaviour.
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