The forced introduction of E20 has set social media ablaze, with outraged car and bike owners complaining bitterly of damage to their vehicles and a drop in fuel efficiency. The anger isn’t irrational. The efficiency drop is real and, going by Autocar India’s own tests, larger than the figures the government itself has acknowledged. 

But while there’s no debate over the mileage penalty, the bigger fear is long-term damage to the vast majority of cars on our roads that are not E20-compliant. It’s a worry fanned by social media and by the way the government has handled the concern. Field trials conducted by the Automotive Research Association of India (ARAI) before the rollout reportedly found no major compatibility issues even in legacy vehicles. 

However, that report has never been made public, which has only deepened suspicion among car and bike owners. Most damaging of all was the Society of Indian Automobile Manufacturers (SIAM) formally flagging alarming levels of contamination in a letter it was later forced to publicly withdraw. Crucially, SIAM’s concern was contaminated fuel carrying worrying levels of chlorine, not the blend itself. That distinction has been lost in the noise, and it sits at the heart of the confusion, even panic, among customers fearing the worst.

So, is E20 the menace it is being made out to be, or is fuel contamination the bigger issue? The fact is, there is no workshop epidemic yet, though sceptics will argue it’s only a matter of time before engines start giving trouble. What social media is amplifying right now is the theoretical damage of a higher blend. That doesn’t make the concerns baseless, since long-term effects take years to show, but the truth is that panic and outrage are currently running well ahead of the evidence. Which makes it worth studying the one country that actually has the evidence, gathered over 50 years: Brazil.

The Brazil experience

If you think India’s leap from E10 to E20 was abrupt, consider what happened there. In November 1975, squeezed by the oil crisis and desperate to protect its foreign currency reserves, the Brazilian government launched Proalcool and shoved its motorists in at the deep end. “The blends with gasoline started at 20 percent. It went very soon up to 30 percent, and it was imposed by the government,” says Peter Gilbert, head of Operational Marketing and Customer Tech Services at Infineum Brazil, a fuel and lubricant additive specialist company whose business, it should be said, depends on ethanol-blended fuels working well. 

The documented history broadly bears him out, with one point worth noting: there was a brief low-blend ramp-up with E10, but that lasted roughly two to three years against the five decades of E20 and above since. Compare that with India, which took nearly two decades from its 2003 blending programme to reach E10. And like India, Brazil never kept an escape hatch. “There was no E0 when E20 was introduced,” says Gilbert, and there is none today: the mandated blend has since climbed through 25, 27 and 30 percent, and since August this year, all pumps in Brazil, including the super-premium ones, dispense E32.

But what is telling is the kind of cars running around on E20 in the late 1970s. Back then, cars were mainly carburetted with no fuel injection, no closed-loop control and no lambda sensors – machinery far cruder than even the oldest E10-era car on Indian roads today. So what broke?

According to Gilbert, remarkably little that could be pinned on E20 itself. “There weren’t any major issues reported,” he says. “There were issues related to the materials of the fuel system, the gaskets and the rubbers used at that time, but that has changed.”

His colleague Leandro Benvenutti, Infineum’s product manager for Latin America, says the trouble in 1970s and 1980s Brazil came almost entirely from dedicated alcohol cars running pure hydrous ethanol (E100), not from petrol cars on E20. “Everything we can remember from that time is related to these alcohol vehicles, not to the gasoline vehicles using E20,” he says. Carburettor corrosion, clogged jets, perished hoses and O-rings: all of it, in their experience, traced back to E100. “If there were problems in the other [non-flex fuel] vehicles, they were really not important at all.”

A caveat both experts volunteer: 1970s Brazil is not 2020s India, and the comparison is not like-for-like. “It’s difficult to correlate to vehicles today,” Gilbert admits. What the Brazilian record offers is not proof that nothing will go wrong here, but a large, long-running natural experiment in which the E20-specific damage everyone feared did not show up.

So what about India’s E10 cars?

Asked what he’d tell a worried Indian owner running an E10-era car on E20, Benvenutti replies, “There is no reason for panic. We don’t expect any immediate impact.” Note the word immediate. The honest answer regarding the long term is unknown, and to their credit, neither of Infineum’s experts pretends otherwise. Over years, rubber components in cars whose materials weren’t specified for E20 may embrittle sooner, and Benvenutti concedes older cars and motorcycles “may see issues with time”. But complicating the issue is attribution – what is due to ethanol and what is not. Rubber parts perish with pure petrol, too. 

Benvenutti recalls his father’s flex-fuel car whose fuel hose dried out and leaked after years of use. “Was that really caused by the ethanol, or was that something going to happen anyway after five or ten years?” If there is a cost to owners, in other words, it is most likely a shortened life for cheap parts such as hoses, gaskets and O-rings rather than failures of expensive ones. “The risk for the metal components, the hard components like valves, injectors and pumps, is much lower if you maintain this product within spec,” explains Gilbert. That last clause matters, and we’ll revisit it.

On material margins, Benvenutti is careful not to overclaim. He believes manufacturers build in buffers. “If I am developing an engine, I would prefer to keep some buffer,” he remarks but adds that he is not a materials specialist and that the buffer may mean a component lasting eight years instead of 10. Whether every manufacturer selling in India engineered that headroom is a question only the manufacturers can answer.

Calibration is key

The more concrete near-term issue isn’t corrosion. It’s calibration. E20 carries less energy per litre, so the engine management system must inject more fuel to keep the mixture correct. Most closed-loop systems that have been around since the move to BS-II fuel-injection in 2000 should easily adapt, but if an older car’s injectors or fuel-trim maps run out of adjustment range, the mixture runs lean. The tell-tale? “Probably the most impactful result will be a light on your cluster. You will see the malfunction indication light on,” says Benvenutti. If your check engine light comes on after the switch to E20, that’s your car telling you it can’t fully compensate. Whether yours will is a manufacturer-by-manufacturer, even model-by-model chance.

Then there is Brazil’s import experience, which is genuinely striking and even reassuring. European and Japanese cars homologated for E10 markets are sold in Brazil and run on E30, now E32, every day. “I haven’t seen any report on issues with those engines,” says Gilbert. And there is no exemption at the top of the market. With no E0 sold anywhere in the country, every Ferrari, Lamborghini and Porsche in Brazil fills up on E32; even the super-premium pumps dispense it. Ask whether a supercar owner can escape the blend, and the answer is emphatic. “No way,” says Benvenutti. 

Low volumes are no excuse to offer a special blend, unlike in India, where supercars have the safety net of a high-priced E0 premium fuel. Benvenutti points out that even a manufacturer bringing in a handful of sports cars must ensure the car is fit for the market’s fuel. “I would not imagine any OEM bringing one unit and selling it if that’s not prepared for that market.” The one genuine weak spot he flags concerns independent, grey-market imports, which arrive exactly as built for the European or Japanese market with no local adaptation. Much of ethanol’s impact is based on anecdotal data rather than any controlled study, but it is decades of anecdotes across millions of cars, from hatchbacks to hypercars.

How much evidence of ethanol impact is there?

Enough of it to take seriously. Start with a fact that rarely features in the Indian debate: Brazil is not a country of new cars. Punishing taxes on new vehicles and tight credit mean Brazilians hold on to their cars for a long time, and the tax system actively rewards them for doing so. Most states have long exempted the oldest cars from the annual IPVA vehicle tax, and a constitutional amendment now makes that exemption national for anything 20 years or older. The result, as per the Brazilian auto components association Sindipeças, is a fleet averaging over 11 years old, with 7.3 million vehicles past 16 years and some 220,000 past 25. Every one of them fills up on E27-to-E32 petrol because nothing else is sold. No doubt, much of this ageing fleet is flex-fuel, engineered from birth to drink anything up to E100, so their survival may seem overplayed, but only up to a point. 

Flex-fuel technology arrived in Brazil only in 2003 with the Volkswagen Golf, which means the country’s first two and a half decades on E20-and-higher blends were served entirely by ordinary petrol cars, and the earliest of those were designed for no ethanol whatsoever; the blend was simply imposed on them, which is exactly what’s happening in India today. The cars that predate the flex era and the imported non-flex cars still running on E32 haven’t seen a trend of ethanol casualties. There is no scrapyard full of ethanol victims; the old cars are still on the road.

Then there’s the formal testing. Before Brazil raised its mandate from E27 to E30 in August 2025, a working group under the country’s Ministry of Mines and Energy ran durability tests on vehicles representative of the national fleet. ANFAVEA, Brazil’s association of vehicle manufacturers (the counterpart to our SIAM), reported that the tests showed no adverse effects on engine durability or performance, with one telling condition attached: provided fuel quality standards are met. Independently, a year-long University of Nebraska-Lincoln study ran E30 in ordinary non-flex-fuel state government vehicles in the US and found no adverse effects either. None of this is a guarantee for every ageing car in India, but it is consistent, multi-source evidence that corroborates Infineum’s findings.

The dangerous C word 

So is the all-clear justified? Only conditionally, and the condition is the same one ANFAVEA attached: clean fuel made and blended to specification. And this is where India’s real problem appears to lie. If genuine damage is occurring in Indian fuel systems, the evidence points not to the ethanol blend but to what’s riding along with it: chloride contamination picked up during the production process and from storage tanks. SIAM’s now-withdrawn letter reported chloride levels of up to 500 ppm in samples from vehicle tanks and 350 ppm at retail outlets, figures the petroleum ministry has vehemently contested. Ministry officials say their own testing found high chlorine levels at just two pumps and that plastic sample containers had corrupted some tests and thrown up false readings. Yet, even a fraction of SIAM’s figures would dwarf the 3 ppm the ministry itself treats as the acceptable ceiling. 

Also, 3 ppm is only a guideline. India has yet to mandate BIS limits for chloride in fuel ethanol – something Brazil has enforced by law at 1 ppm for years. Chlorides corrode fuel pumps, injectors and valves regardless of whether a car was designed for E10 or E20, which is precisely why blaming the blend misdiagnoses the disease. The Brazilian experience, in short, largely acquits ethanol. It says nothing to acquit the fuel quality actually coming out of Indian pumps, and fixing that is a question of standards and enforcement, not of retreating to E10. 

The E20 debate, now thoroughly political, will no doubt rage on: the government and its agencies on one side, and on the other, opposition parties and a swarm of influencers and social media experts riding the outrage for popularity and views, but few of them have bothered to put an independent expert on record. The good thing is that science and first-hand experience – Brazil’s, in this case – take no sides. And that’s the side we are on.