ThrottleJournalEV, Petrol, Diesel or CNG: Which Is Cheapest to Run?
By Chong Sem · Updated 7 November 2026Short answer: an electric car charged at home is by far the cheapest to run, at about ₹1 a km against roughly ₹4.50 for CNG, ₹5.30 for diesel and ₹9.50 for petrol in the same SUV. But the EV costs the most to buy, so it only comes out ahead overall once you've driven roughly 30,000 to 37,000 km. For lower mileages, CNG is usually the cheapest all-round choice.
Running cost per kilometre is only half the question. The other half is how long the fuel savings take to cover a higher purchase price. This guide answers both with one car sold in all four versions, the Tata Nexon, so the only thing that changes is the fuel. Run your own numbers with our EV vs petrol vs diesel calculator as you read.
How we compared them
Comparisons between different models are muddied by size, weight and features. The Tata Nexon is one of the few cars in India offered as a turbo-petrol, a diesel, a petrol-CNG and an electric car, with the same body and broadly the same equipment, so it isolates the fuel.
For efficiency, we use the real-world figures from Autocar India's test of all four Nexons (September 2026), not brochure claims:
- Petrol (DCA automatic): 7.7 km/l in the city, 13.9 km/l on the highway. We use the average, 10.8 km/l.
- Diesel (manual): 17.95 km/l average.
- CNG (manual): 15.1 km/kg in the city and close to 24 km/kg on the highway. We use 19.5 km/kg.
- EV (45 kWh): around 350 km of real-world range, which works out to about 7.8 km per kWh.
For prices, we use Delhi on 7 November 2026: petrol ₹102.12 a litre, diesel ₹95.20 a litre (Mint) and CNG ₹86.98 a kg (Times of India). For electricity, we assume ₹8 a unit at home, all charges included, and ₹17.99 a unit at public fast chargers, the all-India median across 5,776 DC chargers tracked by ChargeDekho in September 2026.
One caveat: the petrol figure is for the DCA automatic, which Autocar found the thirstiest of the four. A manual petrol would likely do somewhat better, narrowing every gap below.
Running cost per km
Cost per km is the fuel price divided by the distance it takes you:
| Version | Fuel price | Real-world efficiency | Cost per km | Cost per 1,000 km |
|---|---|---|---|---|
| Petrol | ₹102.12/litre | 10.8 km/l | ₹9.46 | ₹9,456 |
| Diesel | ₹95.20/litre | 17.95 km/l | ₹5.30 | ₹5,304 |
| CNG | ₹86.98/kg | 19.5 km/kg | ₹4.46 | ₹4,461 |
| EV, home charging | ₹8/unit | 7.8 km/kWh | ₹1.03 | ₹1,026 |
| EV, public fast charging | ₹17.99/unit | 7.8 km/kWh | ₹2.31 | ₹2,306 |
Costs calculated by ThrottleJournal from the prices and efficiency figures above.
Charged at home, the EV costs about a ninth as much per km as the petrol. Even at a median-priced fast charger, it's still under half the cost of CNG. But public prices vary widely. Autocar quotes ₹24 to ₹28 a unit at some fast chargers; at ₹26 a unit, the EV costs ₹3.33 a km, still cheaper than CNG but by much less.
What you'll spend in a year
Multiply cost per km by how far you drive. Here's the annual fuel or charging bill at three common distances:
| Version | 10,000 km a year | 15,000 km a year | 20,000 km a year |
|---|---|---|---|
| Petrol | ₹94,556 | ₹1,41,833 | ₹1,89,111 |
| Diesel | ₹53,036 | ₹79,554 | ₹1,06,072 |
| CNG | ₹44,605 | ₹66,908 | ₹89,210 |
| EV, home charging | ₹10,256 | ₹15,385 | ₹20,513 |
| EV, public fast charging | ₹23,064 | ₹34,596 | ₹46,128 |
At 15,000 km a year, switching from petrol to a home-charged EV saves about ₹1.26 lakh a year in fuel. Switching to CNG saves about ₹75,000. Those are big numbers, but they have to be weighed against what each version costs to buy.
The purchase price gap
Cheaper fuel almost always means a more expensive car. Using Autocar India's September 2026 ex-showroom figures for the Nexon:
- Petrol: ₹7.40 lakh to ₹13.90 lakh.
- CNG: ₹8.35 lakh to ₹13.60 lakh. The base CNG costs ₹95,000 more than the base petrol.
- Diesel: ₹9.15 lakh to ₹14.40 lakh. Autocar puts the premium over an equivalent petrol at around ₹1 lakh.
- EV: ₹12.49 lakh to ₹17.49 lakh. Autocar notes that the top 45 kWh EV costs ₹2.65 lakh more than the top petrol automatic.
On-road prices add registration, road tax and insurance, and these differ between fuels. Many states give EVs road tax or registration concessions, so check the rules in your state, as it can shrink the EV's premium noticeably. Dealer discounts also vary by version and month.
Break-even: when the cheaper fuel pays back
The break-even distance tells you how far you need to drive before the cheaper fuel has paid for the higher price:
Break-even km = extra purchase price ÷ (petrol cost per km − alternative cost per km)
| Versus petrol | Extra price | Saving per km | Break-even distance | At 12,000 km a year |
|---|---|---|---|---|
| CNG | ₹95,000 | ₹5.00 | 19,019 km | About 1 year 7 months |
| Diesel | ₹1,00,000 | ₹4.16 | 24,085 km | About 2 years |
| EV, home charging | ₹2,65,000 | ₹8.43 | 31,436 km | About 2 years 7 months |
| EV, public charging only | ₹2,65,000 | ₹7.15 | 37,067 km | About 3 years 1 month |
Price gaps from Autocar India. Break-even ignores interest on the extra amount, insurance differences and resale value.
Our EV figure lines up with Autocar's own estimate of roughly 32,000 km. The key insight is how strongly it depends on distance. Drive 6,000 km a year and the EV takes over five years to pay back. Drive 20,000 km and it pays back in about a year and a half.
If you're borrowing to buy, remember that a higher price also means a bigger loan. An extra ₹2.65 lakh financed at 8.8% for 5 years adds about ₹5,475 to the EMI and roughly ₹63,500 in interest, which pushes the break-even further out. Our car loan guide explains how to work out that cost.
Five-year cost of ownership
Putting the purchase gap and fuel together over five years at 12,000 km a year (60,000 km in total), measured against the base petrol price:
| Version | Extra price | 5-year fuel or charging | Extra price + fuel |
|---|---|---|---|
| Petrol | ₹0 | ₹5,67,333 | ₹5,67,333 |
| Diesel | ₹1,00,000 | ₹3,18,217 | ₹4,18,217 |
| CNG | ₹95,000 | ₹2,67,631 | ₹3,62,631 |
| EV, 80% home and 20% public | ₹2,65,000 | ₹76,908 | ₹3,41,908 |
| EV, home charging | ₹2,65,000 | ₹61,538 | ₹3,26,538 |
Over five years at this mileage, the EV and CNG both beat petrol by more than ₹2 lakh, and the gap between EV and CNG is small, ₹20,000 to ₹36,000 depending on how you charge. That's close enough that the practical points below should decide it, not the spreadsheet. For a full picture including insurance, servicing and depreciation, use our total cost of ownership calculator.
What if prices change?
Fuel and electricity prices move, so it's worth checking how sensitive these answers are. The surprise is how little the EV's break-even moves with your electricity tariff, because the saving comes mostly from not buying petrol:
| Scenario | Alternative's cost per km | Break-even vs petrol |
|---|---|---|
| EV, home power at ₹6/unit | ₹0.77 | 30,508 km |
| EV, home power at ₹8/unit (our base case) | ₹1.03 | 31,436 km |
| EV, home power at ₹10/unit | ₹1.28 | 32,422 km |
| EV, home power at ₹12/unit | ₹1.54 | 33,472 km |
| CNG at ₹86.98/kg (Delhi today) | ₹4.46 | 19,019 km |
| CNG at ₹95/kg | ₹4.87 | 20,725 km |
| CNG at ₹100/kg | ₹5.13 | 21,953 km |
Doubling the electricity tariff from ₹6 to ₹12 a unit adds only about 3,000 km to the EV's break-even. A ₹13 a kg rise in CNG adds about 2,900 km to its break-even. The petrol price matters more: at ₹110 a litre, the EV pays back in 28,932 km and CNG in 16,595 km; at ₹95, those stretch to 34,103 km and 21,911 km. In short, the cheaper fuels stay cheaper across any realistic price change. What really decides the answer is how far you drive.
How to run this comparison for any car
The Nexon is a convenient example, but the same five steps work for any pair of cars you're considering:
- Find real-world efficiency for each version from road tests or owner reports, not the brochure. For an EV, divide real-world range by usable battery capacity to get km per kWh.
- Use today's prices where you live: petrol, diesel or CNG from your nearest pump, and your own electricity tariff from your latest bill.
- Work out cost per km for each: price divided by efficiency.
- Get on-road quotes for each version from the dealer, including registration, insurance and any discount, and find the difference.
- Divide the price difference by the per-km saving to get the break-even distance, then divide by your yearly km to see how many years it takes.
If the break-even arrives well before you plan to sell the car, the dearer, cheaper-to-run version is worth it. If it arrives after, it isn't, however good the per-km figure looks.
The EV: what the per-km number hides
Home charging is everything
The EV's huge advantage depends on charging at home or at work. In a flat without an assigned parking spot or a society that allows a charger, you'll depend on public chargers, and the saving shrinks. Check this before anything else.
Your home tariff matters
Most homes pay on slabs, so the EV's units are billed at your highest slab. In Delhi, domestic rates run from ₹3 a unit for the first 200 units to ₹8 above 1,200 units, before fixed charges, surcharges and duty. Adding about 128 units a month (roughly 1,000 km of driving) can push a household into a higher slab. Our ₹8 a unit assumption is deliberately on the safe side; many owners will pay less.
Range and road trips
Autocar found the 45 kWh Nexon EV manages around 350 km in real-world use, and the 30 kWh version a little over 200 km. That covers daily driving easily but needs planning for long trips. A fast-charging stop from 20% to 80% on the 45 kWh pack takes about 29 minutes, according to Autocar, and costs around ₹486 at the median public rate.
Maintenance and battery
EVs have fewer moving parts: no engine oil, clutch, spark plugs or exhaust, so routine servicing is generally cheaper. The big unknown is the battery's long-term health and resale value. Check the warranty terms on the battery pack before you buy, and consider how long you plan to keep the car.
CNG: the trade-offs
CNG wins on value for most city drivers at moderate mileages, and Autocar called the Nexon CNG the sweet spot of the range. But know the catches:
- Station availability and queues. CNG pumps are concentrated in certain cities and corridors, and queues at busy stations can be long.
- Boot space. The cylinder takes up luggage room, though twin-cylinder layouts reduce the impact.
- Rising prices. CNG has become costlier through 2026. Mumbai's distributor raised its price to ₹90 a kg from 1 November 2026, its sixth increase this year, reported the Hindustan Times. Each ₹5 a kg rise adds about ₹0.26 a km at 19.5 km/kg.
- Manual only in many models, including the Nexon CNG at the time of writing.
Diesel: who it still suits
Diesel is now a niche choice, but it still makes sense for one type of driver: someone covering long highway distances regularly, often with a full load. It's efficient at steady speeds, has a long range per tank and is quick to refuel anywhere in the country.
Two things count against it. The purchase premium is similar to CNG's while the running cost is higher. And in Delhi NCR, diesel cars face a 10-year age limit, against 15 years for petrol, which hurts resale value there. If you live in NCR, factor that in.
Petrol: when the simplest choice wins
Petrol has the highest running cost but the lowest price, the widest choice of variants and automatic gearboxes, and fuel available everywhere. If you drive under about 8,000 km a year, the cheaper fuels may never pay back their premium before you sell the car. In that case, petrol is the sensible choice, and the money saved up front can go towards a bigger down payment.
If you choose petrol, a few habits cut the bill noticeably. Our guide to calculating and cutting your monthly fuel cost shows how.
Which should you buy?
| If you… | Best fit |
|---|---|
| Can charge at home and drive 10,000+ km a year, mostly in the city | EV |
| Drive 8,000 to 15,000 km a year with good CNG stations nearby | CNG |
| Drive long highway distances often, outside Delhi NCR | Diesel |
| Drive under 8,000 km a year, or need an automatic on a budget | Petrol |
| Live in a flat with no way to charge at home | CNG or petrol, unless public charging is genuinely convenient |
Three questions settle most decisions: How many km do you really drive a year? Can you charge at home? How long will you keep the car? Answer those, and run your own numbers in the comparison calculator and the fuel cost calculator.
Frequently asked questions
Is an EV really cheaper than petrol in India?
To run, yes, by a wide margin: about ₹1 a km charging at home against roughly ₹9.50 for a petrol automatic SUV in our comparison. Overall, it's cheaper only once you drive enough to recover the higher price, about 31,000 km with home charging.
Which is cheaper to run, CNG or diesel?
CNG, on current Delhi prices: about ₹4.46 a km against ₹5.30 for diesel in the same SUV. CNG also costs slightly less to buy, so it usually wins unless you mainly drive on highways or in areas with few CNG stations.
How much does it cost to charge an EV at home?
At ₹8 a unit, a car doing 7.8 km per kWh costs about ₹1,026 to charge for 1,000 km. Your actual cost depends on your electricity slab and your state's tariff.
Is public fast charging expensive?
It costs two to three times more than home charging. The September 2026 median was ₹17.99 a unit, though some stations charge ₹24 to ₹28. Even so, it's usually cheaper per km than CNG.
How many km do I need to drive for an EV to make sense?
For the Nexon, roughly 30,000 to 37,000 km in total, depending on how much you charge at home. At 12,000 km a year, that's about two and a half to three years.
Last updated: 7 November 2026. Fuel prices are for Delhi on 7 November 2026, electricity rates are assumptions explained above, and efficiency figures are Autocar India's real-world test results for the Tata Nexon. All costs are calculated by ThrottleJournal and are for information only.