Diesel vs petrol engine advantages and disadvantages-

Diesel vs petrol engine advantages and disadvantages

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A decision everyone has to make before purchasing a new vehicle is whether to choose a diesel engine vehicle or a petrol engine. Although both of these engines have their own set of advantages, one is better than the other in a few ways. 

 Before moving further, first, have a look at the working of both diesel and petrol engines.


Working of diesel and petrol engine


Petrol and diesel engines are highly similar in structure and working. They both are internal combustion engines that mean combustion will take place inside the chambers. A two or four-stroke cycle is the basis of the working of these engines. 

The point when the fuel enters the combustion chamber till it exits through the exhaust point is known as the power cycle.

This power cycle further includes four phases. 


Different phases of power cycles


1.Intake phase


It is the first phase of the power cycle. In this stage, the air enters into the cylinder for compression.


2.Compression phase


In this phase, the fuel injector injects the fuel into the combustion chamber, and the piston compresses the air-fuel mixture. This air-fuel mixture is ignited that causes an explosion.


3.Power phase


The explosion in the compression phase causes the piston to move downward. This piston further drives the crankshaft and produces motion.



4.Exhaust phase


In this phase, the residual of the burnt air-fuel mixture expels out of the cylinder through the exhaust valve.

After this phase, the Intake phase again starts.

These phases are the basis of the working of both petrol and diesel engines.


Differences in the working of petrol and diesel engine


The difference lies in the way both engines ignite the air-fuel mixture. In a petrol engine, the air-fuel mixture ignites by the spark plug. The ignition system delivers a heavy voltage (up to 20,000) to the spark plug. This heavy voltage ionizes the air around the tip of the spark plug. This ionized air further ignites the fuel in the combustion chamber.

On the other hand, a diesel engine uses no spark plug to ignite the air-fuel mixture. The air inside the chamber is heavily compressed, and this compression increases the temperature of the air. This increase in temperature is up to such an extent that it is enough to ignite the fuel in the combustion chamber.

To sum up the differences between petrol and diesel engine, we have-

  • Petrol engines have spark plugs, while diesel engines have none. 
  • In petrol engine air is not much compressed whereas in diesel engine air is heavily compressed.

Now when you know the difference in working of petrol and diesel engines, we can move on:


Advantages and disadvantages of Petrol and diesel engine




Efficiency is the primary factor in the decision making, whether to choose a petrol engine or a diesel engine.

Diesel engines are up to 20% more efficient than their petrol alternative. There is a direct supply of fuel in a petrol engine. On the other hand, a diesel engine uses fuel only during compression.




Mileage is something every Indian is obsessed with. As we just now saw that in diesel engines, the fuel is used only during compression. Now, this means it has a lower fuel consumption than a petrol engine. Lower fuel consumption means more mileage.




We know that the diesel engine works by high compression of air and fuel. The making of the diesel engine should be strong enough to hold this pressurized air. So the manufacturing cost of a diesel engine increases in the course of making it hard and durable. So, diesel engines are costlier than petrol engines.


4.Maintenance cost


Another factor that comes into play is the service and maintenance cost of these engines.

Diesel engines have to bear much higher compression force, so the wear and tear of the diesel engine will be much more than the petrol engine.

Now, this indicates that you have to spend an extra amount on its maintenance.

On the other hand, the maintenance cost of a petrol engine is low as it experiences less wear and tear.



5.Fuel prices


The last factor to consider while purchasing a diesel or petrol engine is the fuel price. Diesel costs less than petrol on average. The fuel price is also a crucial factor, but only if your driving requirements are much higher, approximately more than 10,000 km annually.


Final words


Now we can have a conclusion to this scenario. You have an almost in-depth understanding of the working, advantages, and disadvantages of both the engines. The diesel engine seems more beneficial by having a look at the advantages and disadvantages. It will not be so if your driving requirements are low and you frequently change your vehicle.

If you change your car more frequently and drive less often, it will be better to purchase a petrol engine car. This decision will save your initial cost. 

If you drive a lot more than a diesel engine car would be better for the long run.

Mukesh choudhary
Mukesh choudhary
Age may offer experience but my passion for cars brings me expertise. I am extremely good at one thing and that's writing about cars.

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