Global crude oil supply has been volatile for some time now, and even more so for the past few months, thanks to the US-Israel-Iran war. While the price kept going up and down, the supply was hampered significantly due to the closure of Strait of Hormuz.
The good thing is that countries around the world have been experimenting with flex fuels for quite some time now—the most popular among them being ethanol. Nations like Brazil, the US, and Thailand have blended ethanol into their petrol for years, cutting import bills and easing pressure on crude reserves.
India has embarked upon a similar path—but since there’s less of a choice involved for the customers on the fuel pumps, it’s got them in a frenzy.
Don’t you worry though—we bring to you all the information necessary and useful. Let’s begin with a simple one.
What is Ethanol Blending?
At its simplest, ethanol blending is the process of mixing ethyl alcohol (ethanol) into standard unleaded petrol.
Instead of filling your tank with 100% fossil fuel, you are using a liquid cocktail that combines traditional petroleum with a plant-based biofuel. The final mixture is measured by volume: for instance, E10 contains 10% ethanol and 90% petrol, while E20 shifts that ratio to 20% ethanol and 80% petrol.
Why is Ethanol Blending Being Done?
Governments are pushing this transition so aggressively because it addresses three critical macroeconomic and environmental pressure points at once.
Energy Security and Sovereignty
Developing nations often import the vast majority of their crude oil. By substituting a chunk of that imported oil with domestically produced ethanol, countries instantly retain billions of dollars within their own economies and protect themselves from global supply blockades.
Decarbonization
Ethanol is a renewable biofuel. As you already know, crops absorb carbon dioxide as they grow. So burning ethanol results in a significantly lower net life-cycle carbon footprint compared to refining and burning ancient fossil fuels.
Supporting Local Agriculture
Ethanol is typically distilled from the fermentation of plant starches and sugars. Farmers gain a massive, consistent secondary market for crops like sugarcane, corn, and damaged food grains that might otherwise go to waste.
How is Ethanol Created & Blended in Petrol?
The journey from a farmer’s field to your car’s combustion chamber follows a highly regulated, high-tech supply chain.
Step 1: Feedstock Processing
Raw agricultural crops (like sugarcane juice or heavy corn starches) are harvested and transported to specialized bio-refineries.
Step 2: Fermentation and Distillation
The plant sugars are fermented using yeast, turning them into alcohol. This mixture is then distilled to remove water, resulting in Anhydrous Ethanol—pure, moisture-free alcohol that is 99.5% pure.
Step 3: Blending in Petrol
Pure ethanol cannot just be dumped into an oil tanker because alcohol eagerly absorbs water from the air. So the blending happens at automated oil company terminals right before the delivery trucks head out to retail fuel stations.
Specialized inline blending systems inject the precise percentage (10% or 20%) into the petrol.
Step 4: In Your Engine
Once inside your car, the blended fuel is pumped to the fuel injectors. Because ethanol contains inherent oxygen molecules, it actually helps the fuel burn more completely inside the engine cylinder. That reduces raw tailpipe emissions like carbon monoxide.
By the time it reaches your car, it’s already a single, uniform fuel with a fixed ethanol percentage, whether that’s 10% (E10) or 20% (E20).
The blend ratio matters because ethanol behaves differently from petrol once it’s inside your engine — it has a higher octane rating but a lower energy content per litre. That difference is what shapes everything from mileage to engine compatibility. Let’s discuss it in detail.
E10 vs E20: What Do These Numbers Mean?
The number after the “E” simply tells you the ethanol percentage in the fuel. In E10, the percentage of ethanol in blended petrol is 10%. And E20 is 20% ethanol and 80% petrol. But the differences go far beyond that.
| Factor | E10 (10% Ethanol) | E20 (20% Ethanol) |
|---|---|---|
| Ethanol Content | 10% | 20% |
| Octane Rating | Around 91-92 RON | Approximately 95-98 RON |
| Energy Content | Higher energy density than E20 | Roughly 6–7% lower energy content than pure petrol |
| Mileage Impact | Minimal, close to pure petrol | Typical drop of 3–7%, more pronounced in older engines |
| Vehicle Compatibility | Safe for virtually all petrol vehicles, including pre-2010 models | Fully compatible with vehicles made from April 2023 onward; older vehicles may see faster wear on fuel-system components |
| Fuel system wear (older vehicles) | Low risk | Higher risk of seal, hose, and gasket degradation in carbureted or pre-2009 vehicles |
| Cost to the consumer | Roughly on par with petrol | Currently priced at parity with petrol in most states |
| Availability (as of mid-2026) | Phased out at most stations | Standard fuel at pumps nationwide |
| Emissions | Lower than pure petrol | Lower than E10, cleanest of the two |
E20 is the more ethanol-heavy, lower-emission fuel that’s now the national default, but it demands slightly more attention from owners of older cars.
On the other hand, E10 was the safer, lower-friction option for any petrol engine—but it’s on its way out as pumps switch over.
Pro Tip
If you’re in the process of buying your first car, make sure to check the filler cap for an E20-compliant tag alongside your regular inspection checklist. You can also find it in the Owner’s Manual.
Indian Government Moving Towards Flex Fuel (E85 & E100)
Despite the customers’ concerns, E20 isn’t the end of the Ethanol saga. The Indian government introduced 20% ethanol blend as the sole choice on the fuel pumps years ahead of schedule. Needless to say, it has brought significant criticism from car owners. But still, the government is in no mood to tap the brakes.
In June 2026, the Ministry of Road Transport and Highways formally amended vehicle standards to legalise E85 and E100 as recognised automotive fuels.
What E85 and E100 Actually are
- E85: 85% ethanol, 15% petrol — a near-complete flip from E20’s ratio.
- E100: Effectively pure ethanol, though commercial E100 typically retains a small petrol/additive component for cold-start stability and flame visibility, rather than being lab-grade pure alcohol.
Already at the Pumps (Barely)
E85 was launched in June 2026, priced significantly lower than regular E20 petrol. But availability is still tiny, with less than 50 fuel pumps delivering it, and the government is planning to expand it.
OEMs like Maruti Suzuki and Hero have already launched WagonR Bio-Flex and Splendor+ Flex Fuel and HF Deluxe Flex Fuel respectively. More manufacturers are planning to launch their flex fuel vehicles shortly.
Cheaper Fuel isn’t Automatically Cheaper Driving
Despite the government claiming otherwise, the lower price tag comes with a real efficiency trade-off. Because ethanol carries less energy than petrol, E85 mileage can drop by 20–35% compared to regular petrol. Moreover, running on E100 can bring mileage down by as much as 27–30%.
Whether that’s a net win depends entirely on the price gap holding. The Indian government has proposed to cut E85’s GST from 18% to 5%, which would tilt the economics further in ethanol’s favour.
Note: Needlessly to say, E85 and E100 is a special flex fuel meant for only certain compliant vehicles. DO NOT fill up your regular vehicle with these fuel types.
Common Concerns With Ethanol Blending in Petrol
The rapid shift from E10 to E20—and the talk of upcoming E85 and E100 flex fuels—has left many Indian vehicle owners feeling anxious. So let’s clear some air.
Can I still get pure petrol at the pump?
Barely. Since April 2026, every fuel station in the country has been mandated to sell only E20 petrol, and pure, unblended petrol has virtually disappeared from regular pumps.
Some oil companies do offer 100-octane premium options like Indian Oil’s XP100, but these are priced well over ₹150 per litre — a significant jump from regular petrol. For daily driving, E20 is now effectively the only option.
Will my vehicle’s mileage drop due to E20 fuel?
Yes. According to the latest reports and claims by the Ministry of Petroleum and Natural Gas (MoPNG) and Ministry of Road Transport & Highways, E20 fuel causes a mileage drop of around 6%. Older vehicles may experience a slightly higher drop.
Because ethanol contains roughly one-third less energy density than pure fossil petrol, the engine has to burn slightly more fuel to produce the same amount of power.
While that means a slight reduction in fuel economy, E20 offers a higher octane rating. That actually the vehicle smoother acceleration, better pick-up, and cleaner internal engine operation.
Note: Some vehicle owners claim higher drop in mileage and damage to the fuel system. But since the claims are unverified, take it with a grain of salt, if you will.
If E20 contains 20% plant-based ethanol, why isn’t it cheaper than regular petrol?
The primary goal of ethanol blending is national energy security, not cheaper pump prices. The Indian government purchases ethanol from domestic sugar mills and grain refineries at fixed, profitable rates to ensure Indian farmers receive fair, reliable compensation for their crops.
When international crude oil prices hover around $70 a barrel, ethanol is actually slightly more expensive to produce than pure petrol. However, the blending program protects the economy by keeping billions of rupees circulating inside India rather than sending them overseas.
The price advantage becomes highly visible when global oil prices spike, effectively shielding Indian consumers from massive price shocks at the pump. But when the crude oil prices are lower, consumers are bound to question the higher fuel prices despite Ethanol blending.
Will using E20 fuel void my car or motorcycle’s warranty?
No, your warranty remains 100% intact. Major automakers—including Maruti Suzuki, Hyundai, Toyota, Hero MotoCorp, TVS, and Bajaj—have clarified that using specification-compliant E20 fuel will not void manufacturer warranties.
Because modern vehicles sold in India undergo standardized testing protocols before hitting the market, manufacturers continue to honor warranty coverage without issue.
What happens if I park my vehicle unused for weeks or during the monsoon?
Ethanol is naturally hygroscopic, meaning it absorbs moisture from surrounding air over time. If ethanol-blended petrol is left sitting in an almost empty fuel tank for several months in humid conditions, water can mix with the ethanol and settle at the bottom of the tank—a process known as phase separation.
To prevent this, keep the tank reasonably full if you plan to leave you vehicle parked for extended periods. Less air inside the tank will mean less atmospheric moisture.
Can I install an aftermarket conversion kit to make my older car a Flex-Fuel vehicle?
It is not recommended or officially supported for everyday passenger vehicles. Converting a regular engine to handle high-blend flex fuels (E85/E100) involves much more than updating software.
You will need to replace non-compliant fuel lines, upgrade fuel injectors, install a specialized Fuel Composition Sensor, and re-tune the Engine Control Unit (ECU).
While aftermarket kits exist for racing or specialized applications, automakers and testing agencies advise against unauthorized retrofits on road vehicles due to safety, compliance, and reliability risks.
The Big Picture: What Ethanol Blending Means for You
E20 Ethanol blending is no longer a policy experiment—it is the standard for modern mobility. While the shift from E10 to E20 and the arrival of Flex-Fuel vehicles can sound complex, the core takeaways are simple.
If you own a vehicle manufactured after April 2023, your engine is fully optimized for E20. You can fill up with complete peace of mind. Older vehicles will continue to run reliably on E20; expect a tiny, barely noticeable drop in mileage, but no sudden engine damage.
Higher ethanol blends reduce our reliance on volatile foreign oil, keep fuel money flowing to domestic farmers, and significantly lower tailpipe emissions.
As India moves toward full Flex-Fuel adoption, the fuel pump will offer more choices than ever. Knowing your vehicle’s specifications is all it takes to drive into the blended-fuel future with confidence.
Stay tuned as we dive into more automotive topics and bring to you more fascinating stories.