6 in 10 new petrol car owners report over 10% drop in mileage: Survey

The reported decline is well above the government's estimated 3-5% impact of E20 petrol, prompting calls for an investigation into possible fuel adulteration or contamination

  A new survey has raised fresh questions about fuel quality in India after a majority of owners of relatively new petrol vehicles reported a significant drop in fuel efficiency. While the government has attributed some mileage reduction to E20 petrol, the survey suggests the decline experienced by many motorists is far greater, prompting calls for a closer investigation into possible fuel adulteration or contamination.

 

The LocalCircles survey, which gathered responses from more than 22,000 owners of petrol vehicles purchased during 2023 and 2024 across 277 districts, found that nearly 59 per cent of respondents said their vehicle's mileage had fallen by more than 10 per cent since early 2025. Out of the total respondents, 25 per cent reported a drop exceeding 20 per cent.

 

 

What did the survey find?

 

According to the survey, responses were distributed as follows:

 

• 25 per cent reported a mileage drop of more than 20 per cent
• 16 per cent reported a decline of 15-20 per cent
• 18 per cent reported a reduction of 10-15 per cent
• 5 per cent reported a fall of 5-10 per cent
• 8 per cent experienced a 1-2 per cent decline
• 18 per cent reported no impact

 

Overall, 72 per cent of respondents said they had experienced some reduction in mileage. 

 

Why are newer vehicles significant?

 

The survey focused on vehicles purchased in 2023 and 2024, which are among the newest petrol cars on Indian roads. LocalCircles says these vehicles should deliver their expected fuel efficiency when using fuel that meets prescribed standards.

 

Since the reported decline is well above the government's estimated 3-5 per cent impact from E20 petrol, the findings point towards possible fuel adulteration or contamination somewhere in the supply chain rather than the ethanol blend itself. The report added that some vehicle manufacturers, including Mercedes-Benz, have also suggested fuel quality may be contributing to the complaints.

 

Older vehicles show a similar trend

 

The survey also compared the findings with earlier LocalCircles surveys involving older petrol vehicles.

 

It found that 66 per cent of owners of pre-2023 petrol vehicles also reported a mileage decline of more than 10 per cent, compared with 59 per cent of owners of 2023-2024 vehicles. According to LocalCircles, the similar trend across both categories suggests the issue is unlikely to be linked solely to vehicle age or engine design. 

What could be causing the problem?

 

The report says one possible concern is the over-blending of ethanol beyond the mandated 20 per cent level. Since ethanol is significantly cheaper than petrol and contains about one-third less energy by volume, excessive blending could reduce mileage without being easily detected through routine checks at fuel stations.

 

LocalCircles also notes that existing density and filter-paper tests used at retail outlets are designed to detect traditional adulterants such as kerosene or solvents, but they cannot reliably identify excess ethanol. It has called for regular blend-percentage testing and greater transparency from oil marketing companies to ensure fuel sold at pumps meets E20 specifications.

 

The organisation said it will submit its findings to the Ministry of Petroleum and Natural Gas and other authorities, while urging independent fuel-quality testing to determine whether fuel being dispensed at petrol pumps complies with prescribed standards. It maintains that only after fuel quality is independently verified can the true impact of E20 petrol on vehicle mileage be accurately assessed.