Difference Between Petrol and Diesel cars and their benefits

When we go and buy a car the most general question customers ask from staff is ‘Is this car diesel or petrol?’, but why do people ask this and which one is the best in use? What is the actual difference Between Petrol and Diesel cars and their benefits?

The car runs with the help of petrol uses the usual spark-ignited internal combustion engine. In a spark-ignited system; the fuel is injects into the combustion chamber and combined with air. This air-fuel mixture ignite via spark from the spark plug. 

Key Components of Petrol Cars

The key components of a car that is run via petrol- 

  • The Battery: The battery of a petrol car helps in providing electricity to start the engine. It also provides electricity to power the electronics/accessories of the vehicle. 
  • Electronic control module (ECM): The ECM helps in controlling the fuel mixture, the ignition timing, and the emissions system of the vehicle. The ECM

1. Monitors the operation of the vehicle; 

2. Safeguards the engine from abuse; 

3. Detects and troubleshoots problems.

  • Exhaust system: The exhaust system expels the exhaust gases from the engine out, through the tailpipe. A three-way catalyst’s designed in order to reduce engine-out emissions within the exhaust system.
  • Fuel filler: A Fuel filler is a nozzle, that arises from the fuel dispenser attaches to the receptacle on the vehicle to fill the tank.
  • Fuel injection system: The Fuel Injection system introduces the fuel into the engine’s combustion chambers. This results in the ignition of the fuel. 
  • line: The Fuel line is a metal tube or a flexible hose (or a combination of these) that helps in transferring the fuel from the tank to the engine’s fuel injection system.
  • Fuel pump: The fuel pump in the vehicle transfers fuel from the tank to the engine’s fuel injection system via the fuel line.
  • Fuel tank (gasoline): The tank stores gasoline on board the vehicle until it’s needed by the engine.
  • Internal combustion engine (spark-ignited): In engine the fuel is injected into either the intake manifold or the combustion chamber. It is combined with air, and the air-fuel mixture is ignited by the spark from a spark plug.
  • Transmission: The transmission aids in transferring the mechanical power from the engine and/or electric traction motor to drive the wheels.

Diesel vehicles are quite similar to petrol or gasoline vehicles. Both of them use internal combustion engines. But there lies one difference, which is, that the diesel engines have a compression-ignited injection system unlike the spark-ignited system used by most gasoline vehicles.

 In a compression-ignited system,

The diesel fuel injects into the combustion chamber of the engine. And is when high temperatures get to achieve. When the engine piston compresses the gas to quite an extent. Many diesel vehicles have an additional after-treatment component, which helps in the reduction of particulate matter. It also breaks down dangerous nitrogen oxide (NOx) emissions into harmless nitrogen and water. 

The exhaust gas of the engine is gets filtered-

through the diesel particulate filter (DPF); and the diesel oxidation catalyst to reduce particulate matter,

diesel exhaust fluid (DEF) gets injects into the exhaust gas mixture.

The resultant filtrate is broken down into nitrogen and water. By chemical conversion within the selective catalytic reducer (SCR). Before it is released into the atmosphere and via the vehicle’s tailpipe.

Petrol or Diesel Cars
Petrol or Diesel Cars

Key Components of Diesel Cars

  • Aftertreatment system: The after-treatment system includes multiple components, which are responsible for acting as the filter for the engine exhaust gas, in order to meet tailpipe emission requirements. 
  • Battery: The battery helps in providing electricity in order to start the engine and power vehicle electronics/accessories.
  • Diesel exhaust filler: The diesel exhaust filler is used in filling the diesel exhaust fluid tank.
  • Diesel exhaust fluid (DEF) tank: The DEF tank holds diesel exhaust fluid, which is an aqueous urea solution. It injects into the exhaust stream; while selective catalytic reduction.
  • Electronic control module (ECM): The ECM comes in handy in controlling the 
  1. fuel mixture
  2.  ignition timing, and 
  3. emissions system.

          It also monitors the –

  1.    operation of the vehicle; 
  2. safeguards the engine from abuse; and 
  3. detects and solves various internal problems.
  • Fuel-
  • filler: Fuel filler is a nozzle from the fuel dispenser that attaches to the receptacle on the vehicle to fill the tank.
  • line: It is a metal tube or flexible hose (or a combination of these) transfers fuel from the tank to the engine’s fuel injection system.
  • pump: The fuel pump transfers fuel from the tank to the engine’s fuel injection system through the fuel line. 
  • tank (diesel): The fuel tank stores the fuel until it’s needed to power the engine.
  • Internal combustion engine (compression-ignited): In this following part, the fuel is injected into the combustion chamber and ignited by the high temperature achieved when gas is greatly compressed.
  • Transmission: The transmission helps in transferring the mechanical power from the engine and/or electric traction motor to drive the wheels.

Automobiles and their engine comes uses two types of fuel -petrol and diesel. These cars have similar functions and components. So why do people think about petrol and diesel while buying a car? The answer is in 4 reasons:

Pricing differences

The knowledge of price while buying is important for buyers. Especially when the price goes on rising and falling on a daily basis. This is one of the basic and important needs for the car which plays a crucial role in running a car. Diesel variant cars usually take more money in comparison to petrol. This higher initial cost has a major significance in the overall economics of choosing a model. If a buyer wants to take Honda city, the top version in Petrol price is Rs.17.40 Lakh whereas in diesel the price is Rs. 23,000 higher than petrol price the price will be Rs.17.63 Lakh, hence proved the difference between diesel and petrol pricing.

Maintenance cost

Maintenance is the necessity of every car because the user should know what is the situation of his car and try to improve its situation by maintaining it or giving servicing of the car. And the relatively higher maintenance cost of diesel models of yesteryear is no longer true now. This was primarily because of the lower quality of the diesel available in India, which used to clog the diesel filters and cause harm to the engine in the long run. The maintenance cost of diesel, when compared to petrol, is still on the higher side but is quite comparable nowadays. So it’s better to prefer a diesel car when the buyer is looking for its maintenance. 

Fuel-Efficient Diesel Motors

Fuel efficiency is very important for buyers to know because it tells whether diesel will consume more or petrol. And since Owing to diesel engine technology, they tend to return more kilometers per litre than a similarly sized petrol motor. This factor tends to be the sole reason the majority of us tend to go for a diesel variant. But, we urge everyone to consider all the mentioned factors before making a decision. 

Now to the important factor of fuel-efficiency, the petrol model is tested to return 21 km/l while the similar diesel variant returns 27 km/l. A difference of six kilometers per litre, in favor of diesel. With fuel prices being adjusted per global crude oil prices every day, we are taking an average difference of Rs 10 per litre between diesel and petrol.

Hence the price of diesel is higher but efficient whereas petrol is lower in price but less efficient. That is why taxis and trucks were of diesel so that they travel long distances. Petrol is for short-distance vehicles like bikes and small cars.

Also Read: 10 popular compact SUVs and their safety ratings compared



An automobile writer. I have done my graduation from Bennett University (Times Group) and writing content for AutoFlipz. And love to drive cars and knowledge about cars.

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