State-run oil marketing companies Indian Oil Corporation , Bharat Petroleum Corporation , and Hindustan Petroleum Corporation have challenged Karnataka government's claims that petrol sold at certain outlets in the state contained 26-31 per cent ethanol, questioning the sampling and testing procedures used to arrive at the findings. The three companies said E20 petrol supplied across their retail networks, including Karnataka, conforms to the Bureau of Indian Standards' IS 17021 specifications, which prescribe an ethanol content of 19-21 per cent.

In a joint statement, the oil companies said the findings cited by the Karnataka government were not supported by tests conducted in accordance with the prescribed statutory and technical procedures. They also questioned the use of third-party laboratory certificates that, they said, did not disclose sufficient details of the testing methodology to independently verify the reported ethanol levels.

The dispute centres on a testing exercise conducted in October 2026 by Karnataka's Department of Food, Civil Supplies, Consumer Affairs and Legal Metrology, which claimed that petrol samples collected from certain retail outlets contained substantially higher ethanol concentrations than the prescribed limit.

The OMCs said the sampling procedure mandated under the Motor Spirit and High Speed Diesel Order, 2005, read with the Marketing Discipline Guidelines 2024, requires six one-litre samples to be collected. Of these, two samples must be handed over to the dealer against acknowledgement, two retained by the oil company or department, and two sent to a laboratory specified under the control order.

Sample labels must be jointly signed, with test results communicated to the dealer and oil company within the prescribed timeframe. While samples collected during a September exercise were routed through the State Level Coordinator to designated OMC laboratories, the companies said the subsequent October sampling was conducted without their representatives. They said they had not received the corresponding retention samples, outlet-wise details or laboratory reports despite seeking them through the state-level coordinator, denying them and the dealers an opportunity to independently verify the findings or seek retesting.

The companies also questioned the testing methodology cited in the laboratory certificates. Under IS 17021:2018, as amended in August 2025, ethanol content in E20 petrol must be determined through specified methods, including Fourier Transform Infrared Spectroscopy, water extraction or gas chromatography under prescribed ASTM standards. Where gas chromatography is used, the standard requires the sample to be diluted in a 1:1 ratio with oxygenate-free petrol and the result corrected against an E10 certified reference material.

The Karnataka certificates, however, merely mentioned ethanol percentage determined through gas chromatography without specifying the applicable test standard, dilution procedure or reference material used, the OMCs said. They argued that the reported ethanol levels of 26-31 per cent could not be independently validated without these details. The companies also flagged discrepancies in the density readings.

The certificates reportedly showed densities of 0.742-0.749 grams per cubic centimetre for samples claimed to contain 26-31 per cent ethanol, against 0.752-0.760 grams per cubic centimetre recorded in E20 samples tested by the OMCs. Since ethanol has a higher density than petrol, a higher ethanol concentration would ordinarily be expected to increase the density of the blend, they said, adding that the discrepancy warranted verification using prescribed testing methods and reference samples.

Seeking to counter the Karnataka findings, the companies cited a nationwide quality-monitoring exercise conducted by the OMCs and the Centre for High Technology , under the Ministry of Petroleum and Natural Gas.

Under the OMC/CHT Quality Coordination Cell exercise, 893 E20 samples collected from depots and retail outlets of the three companies across 27 states and Union Territories were tested at refinery and OMC quality-control laboratories.

All 893 samples were found to contain ethanol within the prescribed 19-21 per cent range, according to the companies.

The results included 56 samples from Karnataka, drawn from different locations and covering all three OMCs. These recorded ethanol content of 19-20 per cent, averaging 19.30 per cent, they said.

The companies said ethanol blending at refineries and depots was carried out through calibrated and automated proportioning systems, with quality-control protocols governing the process.

Blending was not a manual or arbitrary exercise, they added. The companies also questioned estimates cited in the Karnataka controversy that E20 fuel could result in annual consumer mileage losses of around Rs 62,000 crore and vehicle repair expenses of Rs 39,000 crore, taking the combined impact to approximately Rs 1.01 lakh crore. They said such estimates required scientific substantiation and could not be based on a blanket assumption of 10 per cent mileage loss across the country's vehicle population. More than 30 crore two-wheelers and 4 crore four-wheelers have been running on E20 fuel for over three years, while more than 6 crore people visit petrol pumps daily, the companies said.

They argued that the absence of any reported widespread vehicle breakdowns was an important consideration in assessing concerns over fuel quality and vehicle performance. Citing the Petroleum Ministry's August 12, 2025 response on ethanol blending, the OMCs said studies involving the Inter-Ministerial Committee, Indian Oil, the Automotive Research Association of India and the Society of Indian Automobile Manufacturers had examined the performance implications of E20. Vehicles calibrated for E20 could experience mileage reductions of around 1-2 per cent, while certain other vehicles could see declines of 3-6 per cent, depending on vehicle category and calibration, according to the ministry's assessment.

The companies said the Rs 39,000 crore estimate for vehicle repairs also needed to be supported by actual vehicle-performance data, materials compatibility studies and documented repair costs. India's ethanol-blending programme, which began with a pilot initiative in 2001, is aimed at reducing dependence on imported crude oil, strengthening domestic agricultural value chains and improving energy security. The programme has been expanded through successive policy interventions, including the National Policy on Biofuels, 2018, and the NITI Aayog roadmap for ethanol blending.

According to Petroleum Ministry data cited by the OMCs, the programme since the 2014-15 ethanol supply year has generated foreign exchange savings of more than Rs 1.97 lakh crore, substituted approximately 316 lakh metric tonnes of crude oil, reduced carbon dioxide emissions by around 952 lakh metric tonnes and resulted in payments of more than Rs 1.66 lakh crore to farmers.

During the 2025-26 ethanol supply year, which ended on October 31, 2026, the three public sector OMCs procured 1,089 crore litres of ethanol and blended 1,134 crore litres against petrol sales of approximately 5,673 crore litres, the statement said.

The companies also rejected suggestions that they had a commercial incentive to blend ethanol beyond prescribed levels, arguing that additional ethanol procurement would increase their costs.

The three OMCs have asked the Karnataka government to share complete sampling documentation, outlet-wise laboratory reports and details of the testing methodology used to arrive at the reported findings.

They have also sought access to the counterpart samples for independent testing at an authorised laboratory using the prescribed referee method, in the presence of representatives of both the state government and the oil companies.

The companies said they were willing to participate in joint sampling and testing in accordance with the Control Order and MDG 2024, adding that any deviation established through the prescribed procedure would be dealt with under applicable guidelines.