Petrol vs diesel car: Which car is best, petrol or diesel?

Petrol or a diesel car? It is one of the most common dilemmas when you are purchasing a new car. To make an informed decision, you must know the key differences between both petrol and diesel vehicles. For some, petrol cars may be a perfect fit, and for some, diesel cars. It all depends on your requirements. To help you select the right car, this article throws light on the key differences between petrol and diesel cars. Read on for all the information related to petrol vs diesel cars.

Which car is best, petrol or diesel?

It’s a very tricky question as there is no straightforward answer. One has to account for several factors to end the confusion between diesel vs petrol cars. However, knowing the key differences between petrol and diesel cars will make your job easier in selecting the right vehicle for your requirements. And that’s what we are going to address in the following sections of this article.

Difference between petrol and diesel cars

When it comes to petrol vs diesel cars, fuel is not the only differentiating factor. There are several factors that you need to understand to know the overall difference between both categories of vehicles. The below parameters will give you a better understanding of the difference between diesel and petrol cars.

Petro car vs diesel car

Below are the key differences between a petrol car and diesel car.

Example: To give you a better idea about petrol cars vs diesel cars, let’s take an example of the Tata Nexon, which is available in both petrol and diesel variants.

• Price difference

There’s a price difference of Rs. 1.3 lakhs between petrol and diesel variants of the Tata Nexon. The higher initial cost may have an impact on the model you choose. Note that the price difference may vary from one manufacturer to another. The above example is only indicative of the difference in pricing.

• Performance

The petrol variant produces more power than the diesel counterpart when it comes to petrol vs diesel car performance. That translates to quick initial acceleration. On the other hand, the diesel model produces more torque, giving it more pulling power than the petrol model. Hence, the initial acceleration may not be as quick as a gasoline engine, but it packs a punch at the top end of the RPM (Revolutions Per Minute).

• Fuel economy

Diesel engines are more fuel-efficient than petrol engines. This factor may play an important role when choosing between a petrol and diesel variant of a vehicle. However, do remember that a diesel engine requires more maintenance than a petrol engine.

Difference between petrol and diesel engine

The engine is the heart of an automobile. Generally, it is the first thing you look for when glancing through the specifications of a car. The fuel type is the first deciding factor before you shortlist the vehicles when purchasing a new car.

Petrol vs diesel engine

The below table denotes the key differences between a petrol and diesel engine.

Both the petrol and diesel engines are IC (Internal Combustion) engines. However, there are several differences when it comes to the working mechanism of both engines. Below are the details of both the engines.

Also, read: Electric car vs petrol car

Petrol engine

Refer to the points below to understand the working mechanism of a petrol engine.

• A petrol engine works on the Otto cycle.

• It has a spark-ignition system to ignite the fuel.

• It runs on volatile fuels such as petrol.

• A petrol engine has a four-stroke cycle: intake, compression, combustion and exhaust.

• During the intake stroke, the air-fuel mixture is drawn into the combustion chamber via the intake valve.

• The piston compresses the air-fuel mixture during the compression stroke.

• In the combustion stroke, the air-fuel mixture is ignited via a spark produced by the spark plug. The combustion generates power. Hence it’s also called power stroke.

• The exhaust gases are pushed out of the combustion chamber via the exhaust valve during the exhaust stroke.

Diesel engine

The below points explain the working mechanism of a diesel engine.

• A diesel engine works on the Diesel cycle.

• It works on a compression-ignition system.

• It has a four-stroke cycle: intake/suction, compression, power and exhaust.

• In the suction stroke, the air is drawn into the combustion chamber via the intake valve.

• In the compression stroke, the air is compressed by the piston. Due to compression, the air temperature increases.

• Next, in the power stroke, the diesel fuel is sprayed into the combustion chamber via injectors. The fuel ignites due to the hot compressed air and pushes the piston.

• The exhaust gases are thrown out of the combustion chamber via the exhaust valve. It is called exhaust stroke.

Pros and cons of a petrol car

Below are the advantages of petrol cars.

• They are more affordable than their diesel counterparts.

• Many options are available in petrol variants, from small hatchbacks to SUVs (Sports Utility Vehicles).

• Petrol engines offer better initial acceleration. Hence, they are more responsive than diesel engines.

• NVH levels are well contained.

• The cost of maintenance is lower than diesel cars.

• Petrol cars perform better in extreme weather conditions.

Here are some of the disadvantages of petrol cars.

• Lower fuel efficiency when compared to diesel cars.

• Petrol engines cannot be used in heavy vehicles.

• Low resale value in the used car market.

• The cost of petrol is high compared to diesel.

Pros and cons of a diesel car

Here are some of the advantages of diesel cars.

• The running cost is low due to the higher fuel economy than petrol cars.

• Diesel cars produce more torque.

• Longer engine life.

• Commands high resale value in the second-hand car market.

• Full-size SUVs are only available with diesel engines due to the high torque they produce.

• Performs better in high altitude regions as there is no requirement of a specific air-fuel ratio.

Below are the disadvantages of diesel cars.

• More expensive than petrol cars.

• Small cars such as hatchbacks may not be available in diesel variants.

• High NVH levels.

• Maintenance cost is higher than petrol cars. Also, spares of a diesel engine command a higher price tag.

• Diesel engines produce less power and are slightly sluggish than petrol engines.

• Diesel engines produce more harmful gases than petrol engines. 

• Difficult to start a diesel vehicle in extremely cold weather.

Petrol vs diesel: fuel price

One of the crucial factors to consider when choosing between a diesel and petrol car is the fuel price. Diesel is relatively cheaper than petrol. Hence, if you look at the cost of fuel, diesel is the best choice. However, a diesel car commands a high price tag, and the maintenance costs are also high. So, you have to make an informed decision based on your requirements.

Diesel vs petrol price

The below table denotes the price of diesel vs petrol.

Note: Prices as per the Indian Oil Corporation as of 21st September, 2021

Petrol vs diesel car running cost calculator

Calculating the running cost of a petrol or diesel car is pretty simple. However, one has to account for several factors such as driving distance, fuel efficiency and fuel price.

Here is an example of running costs calculation for the Tata Nexon SUV, available in both petrol and diesel variants. Note that we have considered the hypothetical driving distance and the ARAI fuel economy figures.

Tata Nexon XE price (ex-showroom Delhi)

Petrol: Rs. 7.29 lakhs

Diesel: Rs. 8.59 lakhs

Fuel economy of Tata Nexon XE variant

Petrol: 17 kmplDiesel: 21.5 kmpl

Petrol vs diesel price in Delhi as of 21st September, 2021

Petrol: Rs. 101.19/litre

Diesel: Rs. 88.62/litre

Assuming that the vehicle runs for 1,000 km in a month, below is the running cost for petrol and diesel variants.

Petrol variant (Driving distance/Fuel economy x Fuel price): Rs. 5,952

Diesel variant (Driving distance/Fuel economy x Fuel price): Rs. 4,121

Price difference: Rs. 1,831

Now, if you purchase a diesel model, the time required to recover the extra Rs. 1.30 lakhs paid for the diesel variant is almost six years. However, the calculation changes with the increase in the monthly driving distance. This calculation will give you an idea about which variant is better for your driving requirements. The diesel variant makes more sense if the driving distance is on the higher side.

Best-selling petrol and diesel cars in India

Here is the list of best-selling petrol cars in India.

• Maruti Alto

• Maruti Swift

• Maruti Baleno

• Maruti WagonR

• Maruti Dzire

Below is the list of best-selling diesel cars in India

• Hyundai Creta

• Toyota Innova Crysta

• Mahindra Bolero

• Mahindra Scorpio

• Kia Sonet

The verdict

So, which car is best, petrol or diesel? Choosing between a petrol and diesel car may be a tricky task. But with a clear understanding of your requirements, you can make the right choice. Diesel cars have the upper hand due to high fuel economy and low fuel cost. However, the service and maintenance of diesel cars can cost you dearly.

Hence, do not make your choice by considering only the fuel efficiency of a car. Instead, buy a car after calculating the approximate running cost and considering the tenure of the ownership. If you wish to own a vehicle for a long time and your average daily driving distance is around 80-100km, a diesel car is the best choice. On the contrary, if the driving distance is less and you do not intend to own the vehicle for more than 3-4 years, a petrol car makes more sense.

Frequently asked questions

Here are some of the most common questions and their answers related to petrol cars vs diesel cars.

Here are some of the most common questions and their answers related to petrol cars vs diesel cars.

Are petrol cars more powerful than diesel cars?

Yes, petrol cars are more powerful than diesel cars due to the higher RPM and initial acceleration. However, diesel cars have better pulling power due to the higher torque produced by the diesel engine.

Are petrol cars more reliable than their diesel counterparts?

Yes, petrol cars are more reliable than diesel cars. Diesel cars are more likely to break down when compared to petrol cars. The repair job is also complicated due to the complex mechanicals of a diesel engine.

Why does a diesel engine last longer than a petrol engine?

The diesel engine lasts longer than the petrol engine due to the property of the fuel. Diesel is a light volatile fuel, and it also lubricates the engine parts when it burns inside the engine. It results in reduced wear and tear, and hence, a diesel engine lasts longer than a petrol engine.

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