It is not just flipping off the coin and let Head or Tail to decide for buying Petrol or Diesel car. There are several factors to consider before you make a move. As in current market scenario most of the Cars / SUVs available in their petrol and Diesel versions to serve different kind of buyers to suffice their needs and Taste.
Here I would share the difference between the Deisel and Petrol cars from technical and Cost point of view.
Max Power / Max Torque:
Most often the similar size of Petrol engine and Diesel engine have same Power but Diesel engine has almost 1.5 times of Torque.
Lets take an example of Swift Diesel and Swift petrol version. Look at the comparison below
Power @ rpm
Torque @ rpm
75 PS @ 4500
190 Nm @ 2000
85 PS @ 6000
113 Nm @ 4500
As you see the Power of Diesel engine is slightly less than Petrol Engine, but Torque is significantly high. Torque is high in Deisel engine because of their high compression ratio.
The question here is what is the difference Power and Torque?
Physics defines Power as a the rate of work done, hence it is directly related to the speed/maximum speed. Torque is the amount of force applied to rotate something, means amount of force applied to achieve the same speed.
Somebody explained it with the act of reading, basically Power is how much you read and Torque is how you feel about it. Driving fun of Diesel cars are substantially higher than petrol one, specially on highways.
That is the reason why most of heavy transport vehicles (Trucks, SUVs etc) are fueled by Diesel to carry heavy weight easily with good amount of torque and small city cars are preferred for Petrol fuel to be more cost effective and cleaner.
Both types of engines are reliable, but Diesel engines are more robust in different atmospheric condition.
Maintenance cost of Diesel engines are almost 20-30% higher than of Petrol engines.
Performance (Fuel Efficiency):
Diesel’s high octane value is the reason behind better fuel efficiency than petrol, but at the same time Diesel is less environ friendly.
Diesel engines are more noisier than petrol one and generate more vibrations too, though there has been a lot technological advancements. The reason is same again higher compression ratio. In higher speed noise difference is negligible.
Diesel vs Petrol car economics:
If you are a die hard Deisel car lover then definitely you should not look at this part of comparison. But from money point of view you should look at the calculation below. In India Diesel is subsidized hence drive the operating cost of car.
Generally Diesel cars are around 15-20% costlier than their petrol Counter part. For example Swift LDi (Diesel) is around Rs. 90k expensive than Swift lxi (Petrol)
In normal conditions the expense of a hatchback diesel car is around 2 Rs/km and 3.5 Rs/km for petrol car. So after driving more than 50,000 kms you will be able to fill the GAP of cost of car, keeping the 90k extra investment in mind.
One more factor which should be considered is the resale value of car. But that should be considered on the type of car, usage and future plans.
But keep in mind the investment of 1L extra, because you can at-least get 7-9 % interest in this amount even in Fixed deposit without doing any thing. And if you are taking a loan for car, it works in reversible manner.
If on average you drive lesser than 15K in a year (average 40 km a day), then make sense to buy Petrol car.
If your drive is around 15k – 20kms in a year ( around 50 kms a day) then you can choose either.
If your average travel is more than 25K in a year (70 kms in a day) then Diesel cars makes sense.
If you want to toss your vehicle in off roads or hills more often, then Diesel is better choice.
Buying SUVs in Diesel engine is better choice, due to high torque is required for Big size vehicle.