Explainer | E5, E10, E20: What do these ethanol labels actually mean?

Reports of potential downsides from the rollout of 20 per cent ethanol-blended fuel (E20), are sweeping through India’s consumer base, stirring doubts about its readiness for the road and impact and auto engines. From fears of engine damage to worries about fuel efficiency, the transition to E20 has triggered widespread debate over whether the benefits outweigh the costs.

Here’s a breakdown of what the E5, E10, and E20 labels mean and how they affect your vehicles.

What’s the latest

According to a release by the Ministry of Petroleum & Natural Gas on March 20, India achieved the 20 per cent ethanol blending target (E20) around five years ahead of schedule, initially set for 2030.

 

Similar to E20, the target of 10 per cent ethanol blending in petrol was achieved in June 2022, five months ahead of the target during Ethanol Supply Year (ESY) 2021-22.

Since June, ethanol blending gradually increased to 12.06 per cent in ESY 2022-23, 14.60 per cent in ESY 2023-24 and 17.98 per cent in ESY 2024-25 by February 28. So far, no decision has been taken by the government to increase ethanol blending beyond 20 per cent.

In January, Petroleum Minister Hardeep Singh Puri said that E20 fuel was available at more than 9,300 stations in India. The government was on track to cover the entire country by 2025, he said. To boost the adoption of E20 fuel, Prime Minister Narendra Modi had launched it in 84 retail outlets of oil marketing companies across 11 states and union territories in 2023.

What the labels mean

The labels – E5, E10, and E20 – represent blends of ethanol with petrol or gasoline. The numerals indicate the percentage of ethanol blended in the fuel.

E5 = 5% ethanol + 95% petrol

E10 = 10% ethanol + 90% petrol

E20 = 20% ethanol + 80% petrol

Why is ethanol added to petrol?

Ethanol is an alcohol-based fuel, usually made from sugarcane, corn, or grains. Mixing ethanol with petrol can help reduce oil imports, cut CO2 emissions, and support farmers through increased demand for crops like sugarcane.

It reportedly helps reduce waste, as ethanol is not just made from sugarcane, but also from surplus rice, maize, damaged food grains, and agricultural residues.

A Niti Aayog study on life cycle emissions of ethanol assessed that Greenhouse Gas (GHG) emissions in the case of sugarcane and maize-based ethanol are 50-65 per cent lower than petrol. E20 blending helped India reduce emissions by 700 lakh tonnes.

On Monday, the Petroleum Ministry listed the benefits of E20 fuel while also addressing the concerns regarding its adoption in a lengthy post on X.

“The E20 blending significantly strengthens India’s energy security by reducing dependence on crude oil imports. Since FY15, India has saved over ₹1.40 trillion in foreign exchange through petrol substitution,” the ministry said.

The ministry added that ethanol blending is also supporting the rural economy. Payments of over ₹1.20 trillion were made to farmers, thereby creating income and employment opportunities in the agricultural and biofuel sectors.

Is it safe for your vehicle?

Several reports claiming that the use of E20 fuel reduces the vehicle's mileage were being circulated in the media. According to a survey by LocalCircles released on Tuesday, two in three vehicle owners with a vehicle that was purchased in 2022 or earlier opposed the government’s E20 petrol mandate. They said that their vehicle’s fuel mileage had reduced in 2025.

However, the petroleum ministry called these reports “largely unfounded and not supported by scientific evidence or expert analysis.”

Explaining that ethanol is lower in energy density than petrol, the ministry said that there is only a marginal decrease in mileage. The decline is estimated at 1–2 per cent for four-wheelers designed for E10 and calibrated for E20, and around 3–6 per cent in vehicles, the ministry added.

It further mentioned that this marginal drop can be further minimised through improved engine tuning and the use of E20-compatible materials.

Most of the leading automobile manufacturers have already adopted E20-compatible materials. The Society of Indian Automobile Manufacturers has confirmed that E20-compliant vehicles began rolling out from April 2023.

Ride quality and vehicle performance

According to the Ministry of Petroleum, ethanol has a higher octane number (108.5 approx) than petrol (84.4 approx). High-octane fuels (95 RON approx) are better suited for modern, high-compression engines, which results in a smoother and more powerful drive.

Vehicles tuned for E20 fuel can deliver even better performance, thanks to the increased octane content.

Ethanol also has a higher heat of vaporisation, which cools the engine’s intake system. This improves the air-fuel mix, making the engine more efficient.

What BIS requires?

Bureau of Indian Standards (BIS), the national standards body of India, has set formal mandates for ethanol-blended petrol. While IS 15464 (2022) covers the requirements for anhydrous ethanol, the pure ethanol used in blends, IS 17021(2018) specifies the quality and testing criteria for E20 fuel used in spark-ignition engines.

Under the mandate, oil marketing companies need to ensure that the ethanol is homogeneously blended at 19–20 per cent volume. Regular ethanol-content checks via the BIS-mandated water-extraction method need to be done.

What you’ll see at the fuel pumps

E20 dispensers have display labels like ‘E20’ along with RON (octane) value, and BIS certification mark. Oil marketing companies declare ethanol content compliance and blending quality visibly on pump signage. If ethanol falls outside acceptable limits (per company lab tests), sales must be stopped until corrected.

What should consumers look for?

• Fuel label: Confirm the pump displays ‘E20’ and shows the BIS standard mark.
• Octane rating: Should reflect approx 95 or a relevant higher octane value.
• Certification: Look for small icons or text citing compliance with IS 17021.
• Blend confirmation: Some stations may display ethanol percentage.