Petrol vs. Diesel – Which Should I Choose?

June 21, 2009, 10:10 IST by

India is one of the biggest markets for diesel cars. Most of the people prefer diesel engines over petrol ones in this country. Why so? The debate between petrol and diesel engines is as old as the engines themselves. Basically, both engines have their own specialties and anyone opting for either of them is basing that on personal driving experiences. Similarly, CNG and LPG Engines also made their foray in the automobile industry mostly owing to their better fuel efficiency, cheaper running cost and eco-friendliness.

Getting to Know the Petrol and Diesel Engines - Technicalities

A petrol engine is one of the first engines to be used in automobiles. Fundamentally, not much has changed since its inception. Diesel engines were largely used for commercial vehicles like trucks, buses, locomotives, ships, etc. In petrol engines, there is pre-mixing of fuel and air, which eventually results in better efficiency that makes the car run at higher speed and is much quieter but the overall fuel efficiency remains quite low.

On the other hand, diesel engines use compression ignition to burn the fuel which is injected in the combustion chamber after the air is compressed. The calorific value of Diesel is more than Petrol and hence the energy output per unit volume of diesel is better than petrol. The construction of diesel engines is bit more complicated than that of petrol and hence it asks for higher initial investment. Comparatively petrol engine construction is simpler and cheaper than that of diesel, which we can also see reflected in the price of our diesel cars.

What does this technical jargon mean for the common man? Diesel cars are good for those who have long distance commuting on daily basis. Diesel engines give better fuel consumption and deliver better torque. This means diesel engines make everyday driving cheaper and an easy experience. Moreover, diesel cars have run far more miles than the petrol ones before they ask for any maintenance, i.e. running life of diesel engines is much better than petrol engines.

Finally, as a fuel, diesel is cheaper than petrol in India. Even in other countries, we see that the litre price of diesel is significantly cheaper than the petrol’s price.

Diesel cars in India are very popular in India as the Indian auto market is one of the most price sensitive markets. The combination of cheaper fuel, good mileage and long life, explains why diesel engine cars are the favourite choice of cabs and regular long distance driving people. As a consequence of the longer life of a diesel engine, the resale price for such cars is also better. In other words, diesel options always fetch you a better price.

From an environment perspective also, diesel is far better than petrol, as the emissions are less harmful!

We can easily say, that once the car has been bought, diesel is always better for the owner than petrol. However, since the purchase is more expensive, the savings after buying should be more than the extra price paid.

Hence, in order to get the full benefit of a diesel car, you should have run higher distances and not short city-hauls.

Where Do Diesel Engines Lack?

Despite the many good points, diesel models do have their own disadvantages and even after so many technical advancements in the automobile industry, these disadvantages still exist. The most common one is the noise. Diesel cars till date are very noisy and especially make a lot of noise when starting from cold. So if you start your diesel car in winter mornings, your neighborhood can clock their schedules with your office timings. (The reason is due to heavier parts in the engine and the different ignition technique.)

Petrol engine driven cars are certainly expensive but they deliver better driving experience with their smoother and quieter engines. Moreover petrol engine cars are cheaper and faster as well.

On Road– Petrol vs. Diesel Performance

Petrol and diesel engine performances have been talked and researched a lot. Earlier diesel engines offered poor performance compared to the petrol engines. Especially in acceleration, diesel engines were found lacking.

But since the advent of the turbo-chargers a lot of things have changed on the diesel side of the fence. “Direct Inject” and “common rail” engines have been the latest kids on the block. Direct inject engines have taken care of the noise problems to a large extent. They also give better mileage over the older indirect injection models. Common rail diesels use the latest technology of direct injection and are the most recent ones offering more fuel economy and better performance. However, not all auto manufacturers have developed and adapted this technology in their cars in India.

Petrol models give more horsepower which enables them to attain higher top speed and better figures of 0-60 kmph acceleration. The refined driving experience offered by the petrol engines still remains unparalleled. However, please note that the new age Turbo diesel engines, such as the Volkswagen engine, give excellent power and acceleration. For example, the Volkswagen Golf 2.0 TDI top of the range car (not available) in India, delivers whopping 167 BHP, 8 seconds acceleration to 100 km/h and a mileage of 1:20 on highways!

Lastly, the account servicing costs of diesel cars is definitely more any day, though the frequency will be less. However, with the latest technology these costs have been curbed by the manufacturers but it eventually depends which brand you are opting for.

Conclusion

It is clear that once the car is bought, the running costs of a diesel car will be far less than a petrol car. Possible less attractive performance is not that relevant in our busy Indian cities, where noise too is a daily issue to put up with.
Hence, the only serious disadvantage of the diesel car in India is the higher purchase price and hence the only factor to consider for Indians is the daily run rate.

We end with a calculation on how to choose between a diesel or petrol car.

Example of calculation for choosing between a Indica Petrol and diesel

Indica Vista petrol: 1172 cc, 65 BHP, torque 9.8Nm, mileage assumed at 15 kmpl, ex-showroom 4.0 lac

Indica vista diesel: 1248 cc, 74 BHP, torque 19.3Nm, mileage assumed at 15 kmpl, ex-showroom 5.0 lac

Considering the cost of diesel at Rs 35 per liter and Petrol at current rate of 46 Rs per Liter, the analysis of money that can be saved with diesel car can be calculated as below.

Suppose you drive 50,000 KM per year.

The cost of fuel per 50000 KM, i.e. 3333.33 liter of fuel for petrol at 15 KMPL, will be Rs 1,53,333. For that of diesel, it will be Rs 1,16,666. The saving for diesel car will hence be Rs 36,667.

In other words, with this usage, the extra cost of Rs 1,00,000 of diesel car would be earned back within about 3 years. As most people will keep the car for longer, in this usage it would make sense to go for the diesel car.

(In fact, the saving could go up as the general mileage of diesel car might be at around 19KMPL on an average which would amount to 92105 Rs with saving 61228 Rs.)

(I used simplified figures here.)

Thank you for reading this article by Shiva Shankar, B.Engg. (Auto). While there are many more technicalities which can be explored, he has not gone into that here. If you have any questions, or details to add, please do share with us and other readers, as the choice between petrol and diesel is one of the most relevant for car buyers.

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Comments on this article

  • I might be btaieng a dead horse, but thank you for posting this!

    September 14, 2012 by  Gloriane

  • Very informative, but he has not taken the following considerations:1. Interest on surplus of the diesel car i.e cost of the diesel vis a vis petrol2. Maintainence cost of diesel vis a vis petrol3. Service costs of Diesel v/s petrol

    January 21, 2012 by  IRFAN BANDUKWALA

  • Petrol engine driven cars are certainly "expensive" but they deliver better driving experience with their smoother and quieter engines. Moreover petrol engine cars are "cheaper" and faster as well.What does it mean? Expensive or Cheaper? :)

    November 08, 2011 by  Mark IV

  • Clear and precise.Could you advise on swift dzire 2011.

    July 25, 2011 by  Vineeth Uk

  • a complete informatory explanation. Very good abd thank u

    March 18, 2011 by  Sabu

  • WELL SAID,THIS IS THE WAY TO PUT AN SUGGESTION.HATS OFF!!!

    February 20, 2011 by  M R Rajaraman

  • what is the difference between 4 cylinder, 16 valve, DOHC engines (seen in Swift and lot of other carsa)and 3 cylinder (seen in Polo, Micra Petrol etc), 8 valve, SOHC engines (seen in Micra Diesel, it has 1.5 Lit engine), which is better and why?

    January 11, 2011 by  Manish

  • Sir,This was really very informative article. On an average I Travel approx 30-35 kms daily. I owned a Indica DLS, Which I had sold off. I had surveyed the market and had eventually decided for going for petrol engine cars such as figo or swift. Swift LXI is costing around Rs. 5.25 lakhs(on road) and Figo EXI around 4.74 Lakhs. while the average of figo is around 12-13 Kmpl and that of swift around 14-15 kmpl. Than I also gave a look in for Indica vista aqua with quadrajet which was costing around 5.12 lakhs on road. The vista was offering more space and good mileage of around 21 kmpl with drivetech4. The differenc in on road price between figo and vista is around 35 k and swift is more costlier by approx 12 k.I am still undecided what to do kindly advise me accordinglyManish

    January 10, 2011 by  Manish Gupta

  • thanks buddy i appraciate your technical and economical view for indians.

    October 25, 2010 by  Nitesh Sahu

  • i am sanjeev kumar.now i am doing mechanical engg.i am saitsify with you.

    October 02, 2010 by  Sanjeev Kumar

  • Perfect. Make Sence. For heavduty go for diesel but for personal use (Not for too much in role)always go for petrol. Anoher one concern about diesel, if in any sitiation diesel car is not in use for few days like 15 to 30 days could occure a problem.

    September 17, 2010 by  Sajal

  • I think petrol engines are much more efficient and cheaper for a common man in India. What I meant is, You should only go for diesel car if you drive your car 50kms or + in a day. considering the example above If you drive 50000kms in an year (which is not the case for 70% & more personal cars) you save Rs. 36,667 but you should also consider the maintenance cost for your vehicle (for diesel car parts normally 135% than petrol cars and servicing too.) So, I would say if you have a drive of around 25 kms a day go for Petrol car. :)but If you really driving 40 Kms then Diesel Car is for you.

    September 08, 2010 by  Deepak Oberoi

  • Your article is very informative and useful.Please would you clear the common doubt that diesel cars need to be driven daily...or else the engine will die eventually.Is this TRUE with Tata Indica(2005) diesel model that i own ?ThanksPurani

    June 27, 2009 by  Purani

  • The information is enough to convince me for a diesel engine.

    June 26, 2009 by  Vikrant

  • Really very nice info on petrol & diesel engines, its also very clear for which condition the petrol & diesel cars suits for. Nice Technical stuff.....

    June 24, 2009 by  Fayaz Khan

  • I would say forget petrol and forget diesel. Now that CNG Cars are out, why not go for CNG directly. In CNG also, I can sat without a doubt that the CNG Logan of Mahindra Renault can be the most economical, because Logan has a very low running cost even without the CNG. With CNG it will be really cheap.

    June 23, 2009 by  Vivek

  • Hi,Article is very useful.1)I have a Indica Turbo ( with alloy + tubless tyres) which gives me 16kmpl with AC...but now suddenly it dropped down to 12kmpl.Can you suggest a remedy?2) I have been told that with vintage DieselEngines have a higher maintance cost than a petrol engine.REGARDSAnjan

    June 23, 2009 by  ANJANBARUA

  • Dear Sir,Truly illustrative for regular reader like us,giving good idea of car sigment,with fuel option.i would like to know more about Tata Safari Decor Ex as i have bought it recently.Regard:Rama shanker Pandey

    June 23, 2009 by  Rama Shanker

  • I have used both diesel and petrol engined cars and would any day prefer diesel over petrol.Most of the autorickshaws in Ahmedabad run on cng and the fares are cheap ,probably because of lesser runing costs ,is it possible to convert a petrol car to run on cng I would like to know more about the cng and lpg options .

    June 23, 2009 by  Tom Antony

  • Comparision of a diesel engine and petrol engine is more informative u should mention Maintainance cost alsoIt will be useful if u compared diesel, petrol and LpG engine

    June 23, 2009 by  Dr Satya Prasad

  • Hi Mr Alok, The diesel engines mainly emits particulates. The emissions is checked based on particulate emission .Though the emission from diesel engine gives a dark smoke, it wont be much harmful as that of petrol emissions. In petrol engines the exhaust contains carbonmonoxide which is a poisonus gas and harmful if taken in large quantity.

    June 22, 2009 by  Shiva Shankar, CarTrade Expert

  • It is very true - for long distance to use Diesel car. I have a Fiat Palit - multijet, as compared to any other petrol eng. car it gives me a very accleration and milage is 20kmpl. This has earned me a lot on daily running as my daily running is 100kms

    June 22, 2009 by  Ajit

  • How can you say, diesel engines are less polluting than petrol engines? Can you give me some idea?

    June 22, 2009 by  Alok

  • Thanxs for the good article.However you have just compared the running fuel cost without considering the servicing and maintenance cost. It will be more useful if we make the cost benefit analysis over a longer span of say 5 years usage taking into account the interst cost on higher investment, higher servicing and maintenance cost, lower running cost etc and then factor on other qualitative aspects like noise, performance, reliability etc

    June 22, 2009 by  Suraj Prakash

  • Dear Vamsi,Yes, we will be working on an analysis of *all* fuel types next.Thanks for your input,Akshay

    June 22, 2009 by  Akshay, CarTrade Expert

  • Hi Mr Prakash Babu,The calculation is merely an example for any user. Shiva mentioned the following lines:(In fact, the saving could go up as the general mileage of diesel car might be at around 19KMPL on an average which would amount to 92105 Rs with saving 61228 Rs.)(I used simplified figures here.)I hope this is clear for the readers! It is just to explain how one should make his calculation!Thanks,Akshay

    June 22, 2009 by  Akshay, CarTrade Expert

  • In my opinion diesel vehicles are economical if used for commercial purposes when the average daily/monthly mileage is high. For personal use where the average running is low I would rather go for a petrol vehicle.

    June 21, 2009 by  Robin

  • It is good up on his path. But who will pay the maintenance and service cost? So for a middle class in India where the running of four wheeler is minimum petrol cars are well suitable.

    June 21, 2009 by  Xxxx

  • My dear serious readerers, please don't be so serious. Anyhow, thanks for making correction in otherwise good article.

    June 21, 2009 by  Kd Singh

  • Overall a good informative article on a very hot issue of these days. Definitely, there was a calculation mistake which Mr. Prasad Babu has corrected. I owns Maruti Swift VDI. I paid about Rs.72000.00 extra for diesel version. At this rates, the difference will be recovered in 38120 KMs (Mr. Prasad Babu don't be so serious for for few KMs) that depends on your usage. But one thing is clear that you pay only once and save for the rest of the car life. MEHNGA ROI EK BAR AUR SASTA ROI BAR BAR. The more you drive the more you get a feeling that you are saving. This feeling is the ultimate goal of buying a car. You are happy when you drive, you are happy when you visit the Diesel Pump and fill the tank you are happy when the Turbo take charge at 2000 RPM. What else you want from a car. I think one forgets the extra bucks paid at the time of purchase when comes out of the showroom.I have read that diesel engine' life is more than 3.50 lacs kms if taken proper care. Please clarify. Please also inform whether is it advisable to get the engine oil changed after 6-7 thousand kms or it should be as the company advise after 10 thousand.

    June 21, 2009 by  Kd Singh

  • I am giving my own experience, I have Diesel Indica DLE of year 1990 and has 4 gears only. My vehicle is uptodate which even new Indica cannot be compared even on race.I had a race with a best driver than me and I am also bot that bad , but my Indica could overtake that. With all these things what I want to tell you the resale value for Diesel cars are very low compared to Petrol ones. The byback from Compnay offrs me only 75000/- whici is bad.Also I know them maintenace cost is more. Oil is consumed ofter,Filters to be replaced often,shockabsorbers are bad, weight is too much so that the wheels get damaged due to weight if a small hole or stone is passed. I prefer petrol cars that in diesel. Of course there are also other advantages for the Diesel, which is cannot be compared to the disadvantages.Stephen Dias,Goa

    June 21, 2009 by  Estevam

  • In your example calculations you have written as 15kmpl for both petrol and diesel is not true at all. Morever it is not stated clearly that this 15 kmpl mileage gives in city or highway. It is obvious and know every readers that the diesel will give more mileage than petrol ie., 16-18 kmpl from diesel and 10-12 kmpl from petrol cars. I view of this, assuming 50000 km, the fuel cost for petrol and diesel will be (50000/12)*46=191666/- and (50000/18)*35=97222/- respectively. Ths the difference between different fuel will be arround Rs.94444/- and not Rs.36667/- as you said in this article. We are the serious readerers, viewing similar type of articles in the the recent past, writers are check once again before releasing to publish.

    June 21, 2009 by  Prasad Babu

  • If diesel emissions are less harmful than petrol (It may be carbon dioxide vs carbon monoxide), why it is that diesel public vehicles like autos and taxis in metros have been converted in to cng? Why government is not asking for conversion of petrol vehicles to to cng especially because private petrol run vehicles outnumber the now cng run public vehicles?

    June 21, 2009 by  Vidyadhar

  • Really it is a good information for existing serious car buyers. But you have not mentioned about maintenance of deisel cars in your example calculations!

    June 21, 2009 by  Prasad Babu

  • i want to know the maintenance expenses of a diesel car. whether it is advisable to go for a second hand diesel car and if yes, how many years old car/kms. run will be better to purchase.it is heard that diesel cars are more expensive to maintain than a petrol car. pl. clarify

    June 21, 2009 by  Srikanth

  • As per our road conditions, more pickup of petrol engines are not necessary first. As well as for economy sake Diesel engines are good and we do not want to affrid driving in rain seasons too. But my sujection is even petrol or diesel cars with ABS braking is most essential in India. Because so many accidents done by skedding.

    June 21, 2009 by  Ramakrishnan

  • Very Informative, put across in simple way.I would request you to give a comparitive analysis between all the available fuel options like LPG/CNG/Petrol/diesel.This would be very helful in analysis a LPG fitted or CNG fitted car.

    June 21, 2009 by  Vamsi
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