Cars and Bikes

Diesel or Petrol Car Which One is Better?

First decision you have to take while buying a car is whether it will be diesel or petrol one, Understanding performance Difference between petrol and diesel cars will help you when it comes to buying a car. So you can pick the best vehicle for you. The main difference between diesel and petrol engines is that petrol engines use spark plugs to ignite the air-fuel mixture, while diesel engines rely solely on heavily compressed air.


Apart from a fact that diesel engines are more powerful than petrol engines, they also have a higher torque and hence they give a smoother drive. On the other hand, the harshness, noise, and vibrations in diesel driven cars are way higher than that of a petrol-driven car which is a big reason of concern.

Maintenance Cost

The maintenance cost of diesel cars is higher than petrol cars. This is because consumables like engine oil and spares used in diesel vehicles are more expensive.

Cost of Car

The diesel variant of cars cost more than the petrol variant. For cars, which cost less than 10 Lakhs, the showroom price between diesel and petrol variants differs from 1 to 1.5 Lakhs. The difference in the on-road price of petrol and diesel car variants will be even more. This is because the cost of registration for the diesel car is more than that of the Petrol car; the difference is about 1 to 3% depending on the cost of the vehicle and the State wise RTO charges where it is purchased.


The mileage of the diesel engine is more than that of a Petrol engine. A diesel engine does not need a spark plug and thus has higher compression. This makes the diesel engine utilize more fuel as compared to a petrol engine. The better mileage of a diesel engine makes it easy to cover the extra cost of the car paid initially, but with increasing cost of cars, the time required to recover this cost has increased.


Since last one year, the prices of diesel and petrol have seen a big hike in India. In 2017, diesel price was 55.94 Rs. per litre which is now touching 74 Rs per litre. Whereas the petrol was at Rs. 66.91 which is now increased even more. The above statistics show that the difference between both is reducing day by day, soon we will see that there will be no price difference between Petrol and Diesel in the forthcoming years.

Smooth Drive

Petrol Engines Property:

  • In petrol engines, air and petrol are usually mixed in a carburetor before being introduced to the cylinder.
  • Once the air and petrol are compressed, the fuel is ignited via an electric spark.
  • Petrol engines are internal combustion engines, which have spark-ignition.
  • In these engines, air and fuel are generally mixed post-compression.
  • Petrol engines work on the Otto cycle, which consists of two isochoric processes and two isentropic processes.

Diesel Engines Property:

  • When injected into the combustion chamber, the Diesel fuel undergoes spontaneous ignition.
  • These engines work on the Diesel cycle, which consists of a constant pressure process, a constant volume process, and two isentropic processes.
  • The Diesel engine is also an internal combustion engine which is also known as the compression-ignition engine. It is named after Rudolf Diesel.
  • In these engines, the fuel is injected into a combustion chamber and is then ignited by the high temperature of the air in the chamber.
  • The high temperature of the air in the cylinder is due to the adiabatic compression. These engines only compress the air and not the fuel.

In General speaking, diesel cars cost more to buy than petrol cars. However, a diesel engine can be up to 40% more efficient than a spark ignited petrol engine. More pulling power diesel engines offer increased torque. This basically means it has more pulling power from lower revs (you’ll notice the difference when you’re behind the wheel). It’s especially useful to have more torque when towing or overtaking or want to drive in Hilly areas

Emissions from Petrol Vehicles

Emissions from petrol cars have been dramatically reduced by the introduction of catalytic converters, which oxidise pollutants such as CO to less harmful gases such as CO2. When compared to petrol cars without catalysts, catalyst cars have much lower CO, HC and NOx emissions, at the expense of CO2 emissions, which increase due to the oxidation of carbon monoxide to CO2. As a consequence of this, a catalyst car will also use slightly more fuel and become less efficient. However, despite these improvements, petrol cars with catalysts still produce more CO and HC than diesel cars, although exhaust emissions of NOx and particulates are much lower than diesel cars. In fact particulate emissions from petrol cars are so low that they are not routinely measured.

Emissions from Diesel Vehicles

Diesel fuel contains more energy per litre than petrol and coupled with the fact that diesel engines are more efficient than petrol engines, diesel cars are more efficient to run. Diesel fuel contains no lead and emissions of the regulated pollutants (carbon monoxide, hydrocarbons and nitrogen oxides) are lower than those from petrol cars without a catalyst. However, when compared to petrol cars with a catalyst, diesels have higher emissions of NOx and much higher emissions of particulate matter.



  • Even though diesel has more fuel efficiency and mileage than petrol, it’s costlier and often requires repairs which can be expensive.
  • Hence, the better choice between the two fuels depends on the requirements and needs of the buyer as the differences between both the fuels are constantly evolving.
  • For better fuel efficiency, pulling power and overtaking in traffic condition diesel cars are better
  • Life of petrol engine cars is high, they need less maintenance, makes less noise and vibration, generates less pollution and performs good at higher speed

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