Nepal | February 24, 2020

To diesel or to petrol?

Waro Basnet

Pick petrol engine for city commuting, go for diesel for longer drives

petrol pump

Photo: Alex Shrestha/ THT


Petrol or Diesel car? It is one of the first questions all car buyers resolve before they get to other car features. Both engines have their own specialties and anyone opting for either of them is basing on the personal driving experiences. If most of your driving is on long tours, or even off roads, diesel engine could be the way to go — it will be more economical compared to cars with petrol engines. However, if you do not make long trips and only make short one in and around the City, a small petrol car might be more suitable. Overall, it all depends on your preferences, budget, and circumstances. If you are still in dilemma, here are some comparable qualities of both diesel and petrol variants.

Diesel has more output

The major difference between diesel and petrol engines is that petrol engines use spark plugs to ignite the air-fuel mixture, while diesel engines rely on heavily compressed air. In petrol engines, there is pre-mixing of fuel and air that results in better efficiency and makes the car run at higher speed. It is also much quieter but the fuel efficiency remains quite low.

On the other hand, in diesel engines, the fuel and air mixing happens only during the combustion. Due to this reason, diesel engines use a fuel injector. “The calorific value of diesel is more than petrol and hence the energy output per volume of diesel is better than petrol,” says Adhir Kumar Shrestha, General Manager, Advanced Automobiles Pvt Ltd. However, he adds, “Diesel engines produce a knocking sound that is referred to as diesel clatter but it gives better fuel consumption and deliver better torque than petrol engines.”

Petrol car costs less

Diesel cars tend to be more expensive to buy than petrol cars. However, diesel will generally last longer than their petrol counterparts, and can go longer between maintenance. Nevertheless, servicing cost of a petrol variant is relatively cheaper. “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,” says Nabraj Niraula, Product Manager, Cars, Tata Motors.

Both offer relaxing drive

“Diesel engines produce more torque and that gives more acceleration off the line,” says Bhadshah Kumar, Head Mechanic at Auto Parts Repair and Maintenance, Chakra path. The main reason for diesel cars having a much smaller power band is it generally gets more torque but spreads over a smaller area. “This problem is amplified by turbo charging, which all diesel engines use these days to improve efficiency,” adds Kumar. In a diesel car, the maximum torque is available at lower revs, so you can change up earlier and this tends to make for a more relaxing drive.

On the other hand, in petrol engines, the power builds in relation to the revs. Therefore, more usable power is available for a longer amount of time. For more exciting drive, it is difficult to ignore the racier nature of the petrol cars, if they have been tuned for higher performance. “Petrol cars are more efficient than diesel for long-term use if you for shorter trips. If you make longer trips, then diesel is the way forward,” concludes Niraula.


A version of this article appears in print on March 27, 2018 of The Himalayan Times.

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