What is far less debatable is that many owners of older petrol vehicles say they are experiencing a drop in mileage after the nationwide rollout of E20 fuel, the extent varies from one vehicle to another.
Is E20 quietly taking a bigger toll on the mechanical health of older vehicles?
A growing number of owners now say their vehicles are requiring more repairs and showing signs of unusual wear and tear after prolonged use of E20 petrol.
According to the survey, 66 per cent of owners of pre-2023 petrol vehicles said their mileage has fallen by more than 10 per cent since early 2025.
However, LocalCircles notes that several independent real-world studies have reported mileage losses closer to 8-12 per cent in older vehicles.
Whether the E20 ethanol-blending programme is an "ongoing experiment" or not may be open to debate. What is far less debatable is that many owners of older petrol vehicles say they are experiencing a drop in mileage after the nationwide rollout of E20 fuel, the extent varies from one vehicle to another. What remains to be seen is how these non-E20-compatible vehicles will fare over the long term. But beyond fuel efficiency, a more worrying question is now beginning to take centre stage. Is E20 quietly taking a bigger toll on the mechanical health of older vehicles?
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A fresh survey by LocalCircles suggests that it might be
Thomson Reuters's Context earlier reported that only around 20 per cent of new petrol vehicles sold in India over the last 15 years are compliant with E20 (20 per cent ethanol-blended) petrol, based on an analysis of government and industry data.
The survey, which gathered responses from more than 44,000 owners of petrol vehicles manufactured before 2023 across 305 districts, indicates that concerns are no longer limited to reduced fuel economy. A growing number of owners now say their vehicles are requiring more repairs and showing signs of unusual wear and tear after prolonged use of E20 petrol.
More owners now report repair issues than ever before
According to the survey, 55 per cent of respondents said they have experienced an increase in wear and tear or repair requirements since early 2025. That figure has jumped dramatically from 29 per cent in the LocalCircles survey conducted just a month earlier in May 2026.
Among those reporting problems, 24 per cent described the increase in repairs as "major", while another 21 per cent called it "moderate". Only 38 per cent said they had noticed nothing unusual.
If the May survey had rung alarm bells, the June findings suggest those bells are now impossible to ignore.
The survey argues that ethanol's chemical properties may be responsible for these complaints. Ethanol readily absorbs moisture, potentially increasing corrosion in fuel tanks, injectors, pumps and metal fuel lines. It can also gradually degrade rubber hoses, seals, O-rings and plastic components that were never designed to handle a 20 per cent ethanol blend. Over time, these effects could translate into higher maintenance bills, especially for vehicles originally engineered for E5 or E10 fuel.
Mileage complaints continue to climb
The wear-and-tear findings come on top of already widespread complaints about falling fuel efficiency.
According to the survey, 66 per cent of owners of pre-2023 petrol vehicles said their mileage has fallen by more than 10 per cent since early 2025. Just one month earlier, that figure stood at 45 per cent.
Breaking down the responses further, 23 per cent reported mileage losses exceeding 20 per cent, another 23 per cent estimated a 15-20 per cent drop, while 20 per cent said they were seeing reductions between 10 and 15 per cent.
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The month-on-month increase is striking. Owners reporting mileage losses above 10 per cent rose by 21 percentage points within a single month.
LocalCircles attributes the decline primarily to ethanol's lower energy density. Since ethanol contains significantly less energy per litre than petrol, engines need to burn more fuel to produce the same performance. Older engines, which lack the adaptive engine management systems found in modern E20-compatible vehicles, are less capable of compensating for the altered fuel characteristics.
A growing gap between laboratory claims and real-world ownership
The debate has increasingly become one of laboratory estimates versus reality.
The Automotive Research Association of India (ARAI) has estimated that E20 should reduce fuel efficiency by only 1-6 per cent. However, LocalCircles notes that several independent real-world studies have reported mileage losses closer to 8-12 per cent in older vehicles.
The concern now is no longer just how far a litre of fuel will take a commuter, but how long their vehicle itself will last.
What is even more worrying is that in May, the government officially notified fuel standards for higher ethanol-petrol blends, including E22, E25, E27 and E30. While these fuels are not yet available at retail pumps, the move creates the technical framework for their eventual rollout, suggesting that E20 may only be a stepping stone. E20 is the reality today; whether E30 becomes the reality tomorrow remains to be seen. Whether motorists will have the option of choosing anything other than E20 in the years ahead also remains uncertain.
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