Petrol, Diesel, or CNG in the Used Market: What Saves You the Most in 2025

If you’re considering a used car purchase in 2025, your savings across petrol, diesel, or CNG depend on several factors. These include the purchase price of the car, running costs, maintenance expenses, resale value, and government policies. This blog breaks down each of these aspects so you can decide which fuel option makes the most financial sense for your needs.

Petrol vs Diesel vs CNG: Which Offers the Most Savings for Used Cars?

If your primary focus is on long-term savings in the used car market, CNG emerges as the most economical option in 2025. It offers lower running costs, improving resale prospects, and is supported by a growing refuelling network in urban areas.

Diesel cars make sense only if you drive long distances regularly and live outside metros with fewer restrictions. On the other hand, Petrol cars are the most convenient choice if your usage is low and you prioritise easy maintenance.

However, the new GST structure introduced in 2025 makes buying smaller cars and two-wheelers more affordable. The GST rate has dropped from 28% to 18% for these categories, which could lower upfront costs in the used market as well. This shift tilts the scales in favour of petrol and CNG cars in the entry- and mid-level segments, adding another layer of savings beyond fuel costs.

Here’s a quick summary of all the factors that impact these savings, followed by a breakdown of each for better understanding:

Resale Value Considerations by Fuel Type

Used car prices vary significantly depending on the fuel type. In 2025, petrol cars continue to dominate the used car market due to their availability and lower initial cost. Diesel cars once enjoyed popularity but have recently seen a decline in resale value in metro cities due to tighter regulations and shorter permissible usage periods. This has led to higher depreciation of diesel-fuelled vehicles in the used vehicle market.

CNG cars, although less common, tend to be priced slightly higher than equivalent petrol models. This is due to their lower running costs, fuel-saving reputation, and growing demand in cities where refuelling infrastructure exists. The table below shows a comparison of the average used car prices across all three types.

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Running Costs and Fuel Efficiency

A significant factor when considering savings on a used car is how much you spend on fuel. Diesel cars traditionally offer better mileage, but higher maintenance costs and policy restrictions have reduced their appeal.

CNG cars remain the cheapest to run in terms of fuel expense per kilometre, provided refuelling stations are within reach. Petrol cars, while less efficient, strike a balance between ease of use and availability.

• Petrol: Mileage ranges approximately15 to 25 km/l. With current petrol prices, the cost per km is higher compared to CNG.
• Diesel: Mileage ranges approximately18 to 23 km/l. Fuel is cheaper than petrol per litre, but the difference has narrowed in recent years.
• CNG: Mileage averages 20 to25 km/kg approximately. Cost per km is close to half of petrol, making it attractive for city driving.

Here’s a tabular look at each type alongside average mileage and cost per unit.

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Maintenance, Insurance, and Hidden Costs

Above all else, maintenance and upkeep are crucial factors when it comes to used cars. Older diesel cars, for example, could require costly repairs from time to time because of their intricate engines. Petrol cars are relatively cheap to maintain, but they might feel a little costly in their fuel consumption. CNG cars reduce running costs; however, you must consider periodic kit inspections, re-certifications, and slightly higher insurance premiums.

• Petrol: Lower service costs, suitable for those with short-distance daily commutes or low usage.
• Diesel: Higher maintenance, especially in cars over five years old. Parts like injectors and turbochargers can be costly. Ideal for extensive daily use and long distances.
• CNG: Regular kit checks and tank certifications are necessary. Insurance premiums can be slightly higher because of the conversion or factory-fitted kit. Ideal for city driving (provided refuelling is convenient) over long distances.

These costs can add up, so it is essential to budget beyond fuel and purchase price when comparing savings.

Resale Value and Long-term Outlook

Resale value depends on demand, regulatory policies, and the age of the vehicle. Due to easy maintenance and fuel efficiency, petrol engines continue to enjoy steady resale demand in India. Diesel, unsurprisingly, faces some roadblocks for resale in metros but is still a relevant option in non-metros where regulations are more flexible.

CNG cars are gaining acceptance and are likely to enjoy better resale prices in metros that are adapting to them. As reported by the Union Petroleum Minister, India already has over 7,400 CNG stations, and the government has targeted 17,500 outlets by 2030. This only means that the demand for CNG used cars is likely to go up as well.

With increasing emphasis on cleaner mobility, diesel demand is expected to reduce further, while CNG and electric alternatives are projected to grow.

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To Conclude

Your savings in the used car market in 2025 will largely depend on your driving habits and where you live, since these are the main influential factors when it comes to fuel type. If you’re planning to finance your next used car purchase, Poonawalla Fincorp offers flexible Pre-Owned Car Loan options designed to make the process simple and affordable. Apply today!

Frequently Asked Questions

Which is better for long-term use: petrol, diesel, or CNG?

As of 2025, CNG provides the strongest case for long-term savings in the used market. It combines low running costs with improved infrastructure, especially in cities. Diesel is now less attractive in metros because of tighter rules, but it can still work for high-mileage users outside large cities in the long term.

Do CNG cars have higher maintenance costs?

CNG cars generally have moderate maintenance costs. The engine itself is often like petrol variants, but you need to budget for periodic kit inspections, tank re-certification, and slightly higher insurance premiums.

Which fuel type gives the best resale value in the used car market?

Petrol cars currently hold the most stable resale value because of their wide availability and low regulatory risk. CNG cars are improving in resale potential as infrastructure expands, and buyers look for cheaper running costs. Diesel cars face declining resale demand, particularly in metro areas with usage restrictions.