Which of the following is used as a fuel in cars along with petrol?

Question

Prepp Team · Accepted Answer

Understanding Car Fuels and Blends

Cars use various types of fuels to power their engines. While petrol (gasoline) is a primary fuel, other substances can be used either on their own, in dual-fuel systems, or mixed directly with petrol. The question asks which substance is commonly used as a fuel in cars along with petrol, implying a blend.

Analyzing the Fuel Options

Let's look at the provided options and how they are typically used as fuel in vehicles:

Methane: Methane is the main component of natural gas, which is used as compressed natural gas (CNG) or liquefied natural gas (LNG) in vehicles. CNG is a common alternative fuel, but it is usually used in dedicated CNG vehicles or dual-fuel vehicles that can switch between petrol and CNG. It is not typically blended directly into liquid petrol for standard engines.
Ethanol: Ethanol is an alcohol produced from biomass (like corn, sugarcane). It is widely used as a biofuel additive to petrol. Common blends include E10 (10% ethanol, 90% petrol) and E85 (85% ethanol, 15% petrol), which are designed to reduce reliance on fossil fuels and lower emissions. Many modern petrol cars are designed to run on blends like E10 without modification.
Butane: Butane is a component of liquefied petroleum gas (LPG), also known as autogas. LPG is used as a fuel in vehicles, often in systems that allow the car to run on either petrol or LPG. Like CNG, LPG is used as a separate fuel source, not typically blended into the liquid petrol in the fuel tank.
Ethane: Ethane is another component of natural gas. While it is combustible, it is not commonly used as a direct fuel for standard petrol-engine cars, nor is it blended with petrol for this purpose.

Identifying the Correct Fuel Blend

Based on the common uses of these substances as vehicle fuels, Ethanol is the one most frequently blended directly into petrol for use in standard cars. This blending helps to extend petrol supplies and can reduce greenhouse gas emissions.

Conclusion

Considering the options and their typical application as fuel in cars, especially when used "along with petrol" as a blend, Ethanol is the substance that fits this description. Ethanol is widely blended with petrol to create biofuels like E10 or E85.

Common Vehicle Fuels and Uses
Substance	Typical Use in Cars	Used Along with Petrol (as a Blend)?
Methane (CNG/LNG)	Alternative fuel (separate system)	No (used separately or in dual-fuel)
Ethanol	Biofuel additive/blend	Yes (e.g., E10, E85)
Butane (LPG)	Alternative fuel (separate system)	No (used separately or in dual-fuel)
Ethane	Not commonly used as a vehicle fuel	No

Revision Table: Car Fuel Blends

This table summarizes the key point about ethanol blending:

Fuel Component	Primary Fuel Role	Blending with Petrol	Example Blends
Petrol	Primary liquid fuel for spark-ignition engines.	Often blended with biofuels like ethanol.	Pure Petrol, E10, E15, E85
Ethanol	Biofuel, oxygenate additive.	Commonly blended with petrol to reduce fossil fuel content.	E10 (10% Ethanol), E85 (85% Ethanol)
Other options (Methane, Butane, Ethane)	Methane/Butane used as separate alternative fuels (CNG/LPG); Ethane not common.	Not typically blended directly into liquid petrol for conventional car engines.	N/A

Additional Information on Ethanol as Car Fuel

Ethanol is widely adopted globally as a petrol additive primarily for environmental and economic reasons. Its use helps to:

Reduce emissions of certain pollutants.
Provide an alternative market for agricultural products (like corn or sugarcane).
Increase the octane number of the fuel blend, which can improve engine performance and efficiency, although ethanol has lower energy density than petrol.

Engines designed to run on high-ethanol blends (like E85) are called Flexible-Fuel Vehicles (FFVs). However, standard petrol cars in many regions are built to safely run on blends up to E10 or E15.