On August 4, Aam Aadmi Party chief Arvind Kejriwal plans to march to the Prime Minister’s residence over the petrol in your tank. A day earlier on Monday, he had gathered people from Delhi and neighbouring states at a town hall outside Delhi’s Constitution Club, listening to complaints about damaged vehicles and falling mileage. It is the loudest moment yet in a row that has been building for months — and to understand why a fuel blend has put a former chief minister on the street, you have to separate the politics from the engineering.
The trigger is not that ethanol was added to petrol — India has done that for years. It is that drivers feel they were never asked. In 2021, India set a target to bring in E20 — petrol mixed with 20% ethanol — and through 2025 it became the only choice at nearly 90,000 fuel stations, sparking an uproar among owners of older vehicles. For most motorists, E20 did not arrive as a choice next to regular petrol. It simply became the default.
That grievance has now found political shape. Kejriwal is the most visible face, but not the only one. The Congress’s Jairam Ramesh has argued for months that consumers and mechanics are reporting reduced mileage and long-term damage and that the government cannot prove E20 is harmless because no real public data exists. The Congress and Trinamool Congress have gone further, alleging a conflict of interest over the Road Transport Minister Nitin Gadkari‘s family’s ethanol business interests — an allegation that remains unproven and which the minister has outrightly rejected. The dispute has also played out in Parliament, forcing the government to put its defence on the record, which is where its most revealing admission surfaced.
The Issue In Parliament: The Centre’s Submission
In a written reply to the Rajya Sabha on July 29, Road Transport Minister Nitin Gadkari said that in the oldest petrol vehicles — BS-III models, introduced from April 1, 2005, and manufactured before 2016 — some rubber parts and gaskets may need to be replaced when the car runs on E20. That was the government conceding, on paper, that the oldest slice of the fleet does see a real material impact.
But the admission was carefully bounded. Gadkari said those replacements can be easily managed during a vehicle’s routine servicing, and that testing found no significant performance variation or abnormal wear in legacy vehicles, and no issues with drivability, startability, or metal and plastic compatibility. The study evaluating E20 on two- and four-wheelers was done jointly by Indian Oil, the Indian Institute of Petroleum in Dehradun, the carmakers’ body SIAM, and the Automotive Research Association of India. The government also points to scale: Gadkari told the Lok Sabha that over 20 crore two-wheelers and 3 crore petrol cars have run on these blends without documented evidence of widespread breakdowns or damage.
What the submission plays down is the cumulative effect on the vast pool of older vehicles still on the road — the very point critics press hardest.
The Big Mileage Question
This is the number everyone argues about, and even the government’s own figures shift. In August 2025 the Petroleum Ministry said the drop was marginal — 1–2% in four-wheelers designed for E10 and calibrated for E20, and around 3–6% in others. On July 30, Gadkari told the Lok Sabha the fall was 2–6% across BS-III, BS-IV and BS-VI vehicles depending on age and type, but insisted durability and on-road tests showed no failures. The physics is not disputed: ethanol has a lower calorific value than petrol, so engines burn slightly more fuel — a 2–5% dip depending on vehicle type, according to automotive engineers.
The Economic Case The Centre Leans On
The government’s bigger argument sits outside the engine bay. It says E20 delivers better acceleration, better ride quality and roughly 30% lower carbon emissions than the older E10 blend, helped by ethanol’s higher octane and heat of vaporisation. And it points to national savings: in its July 2026 rebuttal, the Petroleum Ministry said ethanol blending has saved more than ₹1.97 lakh crore in foreign exchange, displaced nearly 316 lakh tonnes of crude imports, cut about 952 lakh tonnes of CO₂, and transferred over ₹1.66 lakh crore to farmers since 2014-15. At 20% blending, farmer payments this year alone are expected to touch ₹40,000 crore.
On price, the Centre is blunt: it says E20 is not necessarily cheaper, because ethanol is bought at rates fixed to support farmers, and the aim is energy security, not lower pump prices. The government has said it will not go back to ethanol-free petrol.
The Choice Question — And The Courts
Even if E20 is safe, the protest’s emotional core is that drivers were given no alternative. That argument has already been tested. On September 1, 2025, the Supreme Court — a bench of Chief Justice B R Gavai and Justice K Vinod Chandran — dismissed a PIL by advocate Akshay Malhotra seeking that ethanol-free petrol stay available, with clear labelling at pumps, and a nationwide study on E20’s impact. The petitioner’s counsel argued the largest number of vehicles were never built for E20 and cited a NITI Aayog report flagging damage; the Attorney General opposed the plea, said E20 benefits sugarcane farmers, and alleged a lobby was behind it. The legal door shut, but the political grievance stayed open — and has now marched into the street.
Kejriwal Vs The Centre
That is what Kejriwal’s demands crystallise. He wants both E20 and pure petrol available at every pump, E20 priced lower than pure petrol, and petrol brought below ₹84 a litre — and he has urged people not to buy petrol or diesel vehicles until fully ethanol-ready E100 models are made in India. He has also demanded the Centre make public the very report it cites to claim E20 does no harm. In response, the Petroleum Ministry rejected what it called “misleading claims,” saying there is no verified evidence of widespread engine damage after years of review and use in crores of vehicles.
What The Automobile Industry Says ON RECORD
Here the picture becomes more honest than either camp. SIAM’s executive director PK Banerjee has said plainly that E20 lowers mileage in older vehicles but is not a safety risk, putting the drop at 2–4% and calling claims of a 50% collapse in efficiency “misplaced misinformation.” “Not a single vehicle breakdown or engine failure has been reported,” he said, adding that warranty and insurance claims will be honoured; SIAM represents Maruti Suzuki, Hyundai, Mahindra, Tata Motors and Toyota. But engineers add the nuance the government skips: in older, non-compliant vehicles, ethanol can erode gaskets, rubber fuel hoses and pipes over the long term — not immediately.
What’s Next For Consumers?
Put both sides together and they largely agree on the facts. Your car is not about to break down. The oldest vehicles will need a few inexpensive rubber swaps. Mileage slips a little — noticeably for a handful of old models, barely at all for new ones. What the government’s numbers cannot settle is the grievance driving the march: people were moved to E20 without being asked, and no one has clearly said who pays if an older engine does suffer. On the science of safety, the Centre has the stronger hand. On choice and accountability, though, the question remains: were drivers ever really given a say — and what happens if their older vehicles pay the price?