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Petrol Vs Diesel Vs CNG Car – Which One Should You Buy In 2023 ?

In a battle between Petrol Vs Diesel Vs CNG, prospective customer’s mileage ambition is the deciding factor

New Tata Nexon CNG
Image – Motor Craze

With the Indian economy booming, more people are buying cars than ever before. Covid-19 amplified the pros of owning a car instead of taking public transport. We are seeing steady growth in the automotive industry across segments.

Personally, I am a diesel head. But that doesn’t mean that diesel would make sense for everyone else. Now that petrol engines are getting more frugal and diesel engines are getting rarer, which one should a prospective customer consider? Apart from these two, is CNG better? What does the economics suggest and what are the associated costs? Let’s break it down in detail.

Petrol Vs Diesel Vs CNG Powertrains

Currently, there is not a single car in India that offers petrol, diesel and CNG powertrain choices at the same time. However, there used to be Hyundai Grand i10 Nios and Aura. For the sake of this comparison, let’s bring back an engine combo from the dead, which is Grand i10 Nios Diesel, as petrol and CNG powertrains are still on sale.

Diesel variants for Nios and Aura were axed when Hyundai discontinued Santro. At one particular time, Nios and Aura offered all three powertrain options. Speaking of petrol engines, they are associated with pros and cons. Pros are refinement, smooth running, high power figures and lower upfront investment. Cons include less torque, high fuel price, and lower efficiency.

Petrol Vs Diesel Vs CNG
Petrol Vs Diesel Vs CNG

Diesel engine pros include high efficiency, high torque, low fuel price and overall lower cost of running. Cons include higher NVH levels, higher upfront costs and less power. CNG has similar pros and cons as compared to diesel engines. On top of it, additional cons include a massive reduction of luggage carrying space and capacity.


Nios’ 1.2L U2 CRDi diesel engine displaced 1186cc and developed 74 bhp of power at 4,000 RPM and 190 Nm of torque at 1,750 RPM. It is a 3-cylinder engine that is mated to a 5-speed manual and a 5-speed AMT gearbox option that promises 25 km/l.

Both Petrol and CNG powertrains were powered by a 1.2L Kappa engine that developed 82 bhp of power at 6,000 RPM and 114 Nm of torque at 4,000 RPM when run on petrol. Promised efficiency figure is 21 km/l. With a CNG kit fitted on, this engine developed 68 bhp of power at 6,000 RPM and 95 Nm of torque at 4,000 RPM. CNG powertrain only got a 5-speed manual, while petrol got a 5-speed AMT as well. Efficiency figure is 28.5 km/kg.

Hyundai Grand i10 NIOS
Hyundai Grand i10 NIOS

Economics For 1 Lakh Km Mileage

For the sake of this comparison, we will take manual variants as the CNG powertrain is only offered with a manual transmission. Fuel economy figures are from the OEM and are best-case scenarios. Now that Nios diesel variants are discontinued, we will take the last recorded price. Fuel prices taken for calculations are dated 14th November 2022 in Karnataka. Petrol price – Rs. 101.94/L, Diesel price – Rs. 87.89/L and CNG price – Rs. 80/kg.

1 lakh km is the ballpark that most car owners aim to achieve out of their cars. If a person covers around 1,000 km every month, it would take around 9 to 10 years to cover the 1,00,000 km mark. With a petrol engine under its hood, Nios would consume 4,761.9 liters of fuel when 21 km/l is claimed.

Hyundai Grand i10 NIOS - Petrol vs Diesel vs CNG
Hyundai Grand i10 NIOS – Petrol vs Diesel vs CNG

Nios’ diesel engine would consume 4,000 liters of fuel as it boasts 25 km/l efficiency. With a CNG powertrain, Nios would consume 3,508 kg of CNG fuel with a claimed 28.5 km/kg. Costs associated with a petrol engine to cover a distance of 1,00,000 km would be Rs. 4,85,428. While a diesel engine would cost Rs. 3,51,560 and CNG powertrain would cost Rs. 2,80,640.

Total Cost (Vehicle + Fuel)

Now is the time to calculate the total cost of ownership. This includes the cost of the car along with cost associated with fuel to clock 1,00,000 km on its odo. We will take Sportz MT trim as it is a middle ground for all three powertrains. Hyundai Grand i10 Nios Sportz Petrol MT costs Rs. 8.32 lakh, Sportz Diesel MT costs Rs. 9.56 lakh (last recorded) and Sportz CNG MT costs Rs. 9.39 lakh (all prices on road). For petrol powertrain, total cost is Rs. 13.17 lakh, for diesel powertrain, total cost is Rs. 13.07 lakh and total cost for CNG powertrain is 12.19 lakh.

After taking into consideration RTO taxes and insurance, there is no real difference between costs incurred by petrol and diesel powertrains. However, if your mileage varies and you are clocking 2,000 km or 3,000 km a month, taking a look at diesel and CNG powertrains is definitely advisable. CNG is the most economical even if one’s mileage is only around 500 km a month. But losing luggage space for economy is definitely debatable.

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