What Is Flex-Fuel? Pros, Cons, And Everything You Need To Know

Recently, Flex-Fuel has been gaining traction as an alternate, environment-friendly fuel for our vehicles. Union Minister for Road Transport and Highways, Nitin Gadkari has been emphasizing auto manufacturers to develop flex-fuel compliant engines for their upcoming models.

Government is considering Flex-fuel as a viable alternative fuel to combat rising fuel prices and a more eco-friendly fuel to bridge the gap to the switch to full electrification in the future. But what exactly is Flex-fuel? Here is everything you need to know about Flex-Fuels. Check it out.


Flex-fuel is a viable alternate fuel that combines regular petrol with either ethanol or methanol. This fuel combination is stored in the same fuel tank and is used by the engine as a blended fuel. This is in contrast to CNG fuel systems, which store petrol and CNG in separate tanks and are used separately by the engine.

The ratio of ethanol to petrol can be adjusted to be any combination between absolute petrol and absolute ethanol. The most commonly used flex-fuels use 85% ethanol and 15% petrol, but this ratio can be adjusted to feature more petrol to avoid engine starting problems in cold areas.

Unlike CNG cars, flex-fuel vehicles require minimal modifications to the fuel system and engine to effectively use the fuel. This means that flex-fuel compatibility has to be factory-engineered and can’t be fitted in the aftermarket. Modifications to the fuel system and engine are meant to make the engines resistant to ethanol, which can be corrosive to engines. 

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Here’s a list of advantages that flex-fuel provides to consumers and environment:

Cleaner Fuel

Flex-fuel features a blend of ethanol and petrol, and thus it is a cleaner burning fuel than pure petrol or diesel. This is because ethanol is a cleaner fuel that produces fewer toxic fumes and particles when burned. This helps flex-fuel be a more eco-friendly fuel that will help reduce emissions in polluted cities.

Flexible Usage

Flex-fuel engines are designed to work on any combination of ethanol and petrol. This means there’s no restriction for using a specific fuel like CNG and so you can use any available fuel, including pure petrol in flex-fuel engines. This fuel provides the flexibility to use pure petrol when in rural areas or using a high blend in the city. 

Sustainable Source

Ethanol and methanol are more sustainable fuels that are sourced from food crops like corn and sugarcane. This reduces the overall cost of the fuel while at the same time reducing the carbon footprint from processing the fuel.

Similar Performance

CNG-fuel cars are known to produce less power than petrol vehicles. But this is not the case with flex-fuel cars, as they still use some petrol in the fuel, which provides similar, and sometimes better, performance than pure petrol vehicles.

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Well, this new full technology looks perfect but there are some drawbacks too. Here, we have mentioned some of the major disadvantages of flex-fuel.

Lower Mileage

Ethanol burns cleaner, but it also contains less energy than pure petrol. Thus, a flex-fuel car will use more fuel as compared to an all-petrol car. However, as flex-fuel is expected to price lower than the petrol/diesel, it can help offset the costs of a lower mileage. 

Mass Adoption

The biggest barrier to flex-fuel adoption is the infrastructure investment required to make the switch in the country. Current engines are not fully compatible with flex-fuels, which means Fuel stations will need to cater to both pure petrol and flex-fuel cars by adding required infrastructure. Car owners will also be slow to adopt the fuel as most of them can buy flex-fuel cars after selling the old petrol cars. This phenomenon also slows down the rate of adoption for this new technology.

Increased Engine Wear

While the flex-fuel engines will be designed to adjust to the blend of fuel used, the ethanol component in the flex-fuel will cause greater wear and stress on engines. This can translate to higher maintenance costs during the time the technology matures and improves reliability.

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The Indian government is proposing regulation to direct car makers to introduce flex-fuel cars by the end of 2022. We hope that we have answered all your questions about the flex-fuel technology…

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