Petrol vs Diesel : Efficiency and Cost of Running

If you’re about to buy a new car, it’s not easy to decide whether to go for a petrol or a diesel model. In the past, diesel engines were seen as being noisier and slower than their petrol counterparts. But technological advances mean this is no longer necessarily the case. What is important, is the cost of ownership of the two engine types and that analysis comes down to how efficient the engines are.
Here’s our take on “Petrol vs Diesel : Efficiency and Cost of Running”

Diesel Seduction

Historically, diesel cars have been more efficient than petrol ones. They simply burn fuel in a more efficient manner, which means less used per mile. Many motorists are seduced into buying diesel cars because they tend to consume less fuel. But the lure of the numbers can be a false economy. Diesel models typically cost more to buy than a petrol equivalent, however diesel fuel is less expensive to buy than petrol. That said, with the introduction of higher-tech turbocharging systems the petrol world is catching up in this respect. In general, you’ll find petrol more efficient than diesel over a medium-to-long term of ownership if you predominantly do shorter trips. If you travel more on the motorway for longer distances, diesel is the way forward.

Now, for Some Numbers

Calculate cost of running

There are five factors to consider before choosing the fuel type for your car – car price, price of fuel, efficiency, maintenance cost and years of ownership. Mileage is the most important factor of the calculation. You need to determine how much you will drive your car every year to get your calculations right. For our studies, we have considered the Honda City as we did last week with respect to the performance.

The City Diesel comes at a price of 8.44 lacs and the Petrol at a price of 7.22 lacs. Recent studies show that 80% of cars bought in India paid using loans. Taking that in mind we have assumed that a loan amounting to 6 lacs has been taken on the Diesel variant and a proportional (to the price) loan of 4.78 lacs on the Petrol. The monthly EMI for a period of 5 years at 12% on the petrol is approximately 10k where as 13k on the diesel. Additionally, we have assumed that the prices of fuel remain constant.

Maintenance cost  for a diesel is about 50% more expensive than that of petrol and are assumed at 15k and 10k per annum. The reason for this is that diesel engines have parts which aren’t present in a conventional petrol engine.

The ARAI values for the City are 17.4 kmpl and 26 kmpl on petrol and diesel respectively however in real life situations it is highly optimistic to expect the car to deliver the same. Thus the efficiency of petrol has been taken as 15 kmpl and 20 kmpl for diesel.

Take for example, that each car was driven for 1000 Kms. Due to the initial expenses the cost of running for the diesel is considerably higher than the petrol. Over time though the diesel catches up to the petrol in terms of overall expenses. However in this case, the recovery period on the diesel is much longer i.e. 9 years. It would therefore be much more economical to go for a petrol vehicle if your daily needs do not require you to traverse long distances.

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The next two examples are for vehicles which have run for 1500 kms/month and 2000 kms/month respectively.

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The inferences from the graphs are pretty straightforward. If the car is run for 33 kilometers daily, Petrol engines appear to be the better choice as they are cheaper to run for nearly 9 years. Diesels, on the other hand, show their advantage once you go considerably above the daily 33 kilometers mark. Diesels not only become cheaper than petrols to run, but also give better value for the high mileage usage In short, for short distance usage, petrol is the obvious choice and if you’re daily usage involves long distances, diesel is a better value proposition.

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See Tips on how you can maintain your Diesel Car