When Krishna Kumar pulled into a petrol station in New Delhi a few months ago, he expected nothing more than a routine fuel stop. Instead, like millions of motorists across India, he found that E20 petrol – a blend containing 20 percent ethanol – was the only fuel available.

He had little choice but to fill up.

Within weeks, the bank employee began noticing changes in the way his petrol sedan behaved on the road. His sedan, which had always been serviced on time and had never given him big problems, no longer felt as responsive. Its fuel efficiency declined, acceleration became sluggish and driving uphill or with the air conditioner on seemed noticeably different.

The mileage, he said, dropped from about 18-20km (11-12 miles) per litre (0.26 gallons) to about 16-17km (10-11 miles) per litre – a drop of more than 10 percent. “The acceleration is slower, especially while overtaking, driving uphill or using the air conditioner,” he said. He hasn’t changed the way he drives; all that has changed is the fuel.

Kumar’s plight is one that millions of car owners across India are suffering as the country completes one of the world’s fastest transitions to higher ethanol-blended petrol.

Under the National Policy on Biofuels, the government of Prime Minister Narendra Modi advanced its target of achieving 20 percent ethanol blending from 2030 to 2025. E20 became mandatory across petrol stations last year. Despite initial concerns over the rush – India had, until then, had a maximum of 10 percent ethanol in its petrol – flagged by several consumers, calls for a review of the policy died down.

But in June 2026, the government’s attorney general told India’s Supreme Court that the Modi administration was “experimenting” with a 20 percent ethanol blend. Even though the government later claimed that the attorney general had been misunderstood, the comments led to national outrage, with car users, opposition politicians and analysts – including a number of commentators politically aligned with the Modi government –  questioning the policy.

The government argues that the 20 percent ethanol blend will reduce dependence on imported crude oil, strengthen energy security, lower greenhouse gas emissions and create new income opportunities for farmers through increased demand for crops such as sugarcane and maize.

But consumers and critics point out that vehicle mileage has dropped – a claim that federal Minister of Road Transport and Highways Nitin Gadkari has accepted – and some have alleged that the cocktail fuel has damaged car parts. Opposition parties have also accused Gadkari of a potential conflict of interest – his family is involved in companies linked to ethanol production.

Yet at the heart of the national debate that the E20 petrol-ethanol mix has triggered is a single question that many are asking: Why has the government pushed through this fuel in such a rush?

“While I understand the government’s push for cleaner fuels, I believe more awareness is needed about how E20 may affect older petrol vehicles,” Kumar said. “Car owners should be properly informed so they can make the right decisions and avoid unexpected changes in performance and fuel economy.”

Less powerful cars

Supporters of the government’s move describe the initiative as a key milestone in India’s clean-energy transition. Critics, however, argue that many consumers are experiencing the immediate costs through lower fuel efficiency, concerns about vehicle compatibility and uncertainty over long-term maintenance.

The rollout has especially raised questions about millions of older petrol vehicles that remain on Indian roads. Automobile manufacturers began introducing E20-compatible materials in new vehicles from 2023, while fully E20-compliant models entered the market from 2025. Although the government says older vehicles can safely use E20 with routine maintenance, many owners remain unsure about the long-term impact on engines that were not originally designed for higher ethanol blends.

One such owner is Anas Khan, a businessman in New Delhi, who says he has noticed a clear difference in both mileage and engine performance after switching to E20 fuel.

“I own a 2021 Maruti Suzuki Baleno, and I have definitely noticed a drop in mileage,” he said, referring to his sedan. “Earlier, my car used to give about 18km per litre, but now it is down to nearly 15km per litre. The pick-up has also become slower, especially while overtaking or driving in city traffic.”

According to independent automobile expert Sajad Ahmad Wani, the effects of using E20 depend largely on the design and age of the vehicle. “Vehicles that are not E20-compatible are unlikely to develop problems immediately after switching to the fuel, but with continuous use over time, ethanol can accelerate the wear of rubber hoses, seals, gaskets and certain fuel system components if they were not designed for higher ethanol blends. Motorists may also notice a slight drop in mileage.”

That mileage should drop with higher ethanol content in the fuel is no surprise.

Ethanol contains less energy per litre than conventional petrol, meaning engines generally require slightly more fuel to produce the same amount of power. While government agencies describe the reduction in fuel economy as marginal for E20-compatible vehicles, experts say the actual impact varies depending on vehicle age, engine design, driving conditions and maintenance.

Wani said many motorists “still do not know whether their vehicles are E20-compatible or what changes they should realistically expect after switching to the fuel”. Car manufacturers and government agencies, he said, needed to do more to communicate with vehicle owners.

Bilal Ahmad, a mechanic, said he too has recently seen more customers reporting reduced mileage and engine performance.

“Many vehicle owners who visit my workshop also tell me they are getting lower mileage than before. From my experience, there seems to be a connection between the newer fuel and the problems some petrol vehicle owners are facing, although the impact may differ from one vehicle to another.”

Long-term impact

The Indian government has disputed most concerns voiced by motorists and mechanics.

The Ministry of Petroleum and Natural Gas (MoPNG), in a recent statement, said assertions that E20 petrol harms engines or substantially reduces mileage are “largely unfounded and not supported by scientific evidence”.

The ministry cited studies conducted by the Automotive Research Association of India (ARAI), the Indian Institute of Petroleum (IIP) and oil companies that found no significant differences in engine performance, power output, engine wear and other parameters, including in older vehicles.

According to the ministry, E20-compatible four-wheelers experience only a marginal reduction of about 1 to 2 percent in fuel efficiency because ethanol contains slightly less energy than petrol. It also said any long-term material degradation can generally be addressed through routine replacement of inexpensive rubber components during regular servicing.

Union Transport Minister Nitin Gadkari has also strongly defended the government’s ethanol policy.

Speaking at a magazine event recently, Gadkari said multiple industry bodies had concluded that E20 is safe for cars. According to Gadkari, the ethanol blending programme has delivered benefits beyond the transport sector by creating a larger market for crops such as sugarcane and maize, increasing farmers’ incomes while reducing India’s dependence on imported crude oil.

But independent analysts say the reality is more complex.

Energy experts say India’s nationwide rollout of E20 petrol has largely been successful from a supply perspective, but they acknowledge that the transition involves trade-offs that motorists are beginning to experience.

“From the supply side, I think India was prepared enough for the rollout of E20 petrol. There has been no disruption in its availability at petrol pumps, and the rollout has been going smoothly. So, from the perspective of fuel supply and availability, I don’t see that as an issue,” said Shyamasis Das, research fellow for energy, natural resources and sustainability at the Centre for Social and Economic Progress (CSEP), a New Delhi-based think tank.

“The main trade-off lies elsewhere,” he added, however.

Because ethanol blending leads to fuel with less energy per litre, and because mileage drops as a result, vehicles need more fuel to cover the same distances they did with lower or no ethanol mixed.

That in turn means that while India’s crude oil demand might fall, it won’t drop by as much as the levels of ethanol blended into petrol, Das pointed out.

“Another important aspect is that anhydrous ethanol [very pure ethanol] is corrosive in nature,” he said. “Engine components therefore need to be resistant to its corrosive effects.”

While newer vehicles are designed to be compatible with E20 petrol, Das said there was still no consensus on the impact of the blend on older or non-compatible vehicles.

The farm factor

Environmental experts caution that the E20 programme also raises broader sustainability questions. While ethanol can reduce lifecycle greenhouse gas emissions compared with conventional petrol, expanding the cultivation of water-intensive crops such as sugarcane may place additional pressure on already stressed water resources in several parts of the country.

Others have also questioned the long-term implications of farmers moving from food crops towards fuel production if that becomes more lucrative.

Maharashtra, one of India’s largest sugar-producing states, has emerged as the country’s leading ethanol producer because of its extensive network of cooperative and private sugar mills. Government incentives, soft loans for new distilleries and assured procurement by public sector oil marketing companies have encouraged rapid investment in ethanol production, making the state central to India’s biofuel strategy.

The expansion of the sector has also renewed scrutiny of the political economy surrounding ethanol production.

For decades, Maharashtra’s sugar industry has been closely linked with regional politics. As ethanol production has expanded, questions have been raised about who benefits most from government incentives and whether the rewards of the clean-fuel transition are being shared equally.

Among the strongest advocates of ethanol has been Transport Minister Gadkari. However, his support for the programme has also attracted criticism because members of his family have commercial interests in companies involved in agro-processing and ethanol production, including CIAN Agro Industries and Manas Agro Industries.

Opposition parties, particularly the Congress, have argued that this creates the appearance of a conflict of interest, suggesting that policies promoting ethanol could indirectly benefit businesses connected to the minister’s family.

Gadkari has consistently rejected those allegations. He has said ethanol pricing, procurement and blending decisions are taken collectively by the Modi cabinet and implemented through state-owned oil marketing companies rather than by him personally. He has also maintained that businesses linked to his family account for less than 0.5 percent of India’s total ethanol production and has dismissed the allegations as politically motivated.

For many observers, however, the debate extends beyond politics.

Consumer groups have called for clearer disclosure of ethanol blend levels at petrol stations and on fuel receipts, arguing that motorists should have better access to information about the fuel they are purchasing and whether their vehicles are compatible with it.

India’s experience also differs from countries such as Brazil, where ethanol has been used for decades alongside widespread adoption of flex-fuel vehicles specifically designed to run on varying ethanol blends. In India, by contrast, the transition to E20 is taking place while millions of older petrol vehicles remain in service, making vehicle compatibility and consumer awareness far more significant issues.

For motorists like Krishna Kumar and Anas Khan, the debate is about more than energy policy or environmental targets. It is about the everyday experience of driving a vehicle that, in their view, no longer performs the way it once did.

“Even though my car is only a few years old and is regularly serviced, it doesn’t feel as smooth or responsive as before,” Khan said.