CNG vs Petrol vs Diesel vs EV Running Cost Calculator (India) — Per km & Payback
Compare what a car costs to run per kilometre in India on petrol, diesel, CNG and electricity at your local prices and mileage figures, the monthly and annual fuel bill for your usage, the payback period of a CNG kit or the EV price premium, the effect of CNG's reduced boot space and range, maintenance differences, and the break-even monthly kilometres for each choice.
How it works
fuel ₹/km = price ÷ mileage (₹/L ÷ km/L, ₹/kg ÷ km/kg, ₹/kWh ÷ km/kWh) · total ₹/km = fuel + maintenance (petrol ≈ 0.6, diesel 0.8, CNG 0.75, EV 0.3) · monthly saving = (petrol − alternative) × km · payback months = premium ÷ monthly saving · break-even km/month = premium ÷ (saving per km × months)
The running cost of a car is its fuel price divided by its mileage, and on that measure Indian prices rank the options in a stable order — electricity at home is cheapest per kilometre, CNG next, diesel, then petrol — with maintenance nudging the gaps. What differs is the entry price: a CNG kit costs under a lakh and pays back within a couple of years at typical city mileage, while an electric car's premium of several lakh needs high monthly distances and home charging to recover within the ownership period, and diesel's premium has become hard to justify below heavy highway use. The break-even kilometres per month is the honest way to choose, before the practical costs of boot space, range and charging access are weighed.
Worked example
At 1,500 km a month with petrol at ₹104 (16 km/L), diesel ₹91 (20 km/L), CNG ₹78 (24 km/kg) and home electricity ₹8/kWh (7 km/kWh), the fuel-plus-maintenance cost per km is ₹7.10 petrol, ₹5.35 diesel, ₹4.00 CNG and ₹1.44 EV — ₹10,650, ₹8,025, ₹6,000 and ₹2,160 a month. A ₹90,000 CNG kit pays back in about 19 months; a ₹4 lakh EV premium in about 3.9 years (needing ≈ 1,180 km/month to recover in five); the ₹1.2 lakh diesel premium takes about 3.8 years.
Frequently asked questions
Does public fast charging kill the EV advantage?
Largely: at ₹20/kWh an EV costs about ₹2.9 per km in electricity — still below petrol but close to CNG, and the premium takes far longer to recover. The EV case rests on home or workplace charging at domestic tariffs.
Factory-fit CNG or retrofit?
Factory kits cost more but keep the warranty, come with a tuned ECU, a properly placed tank and RTO papers in order; retrofits are cheaper (₹40–60k), often void the warranty, need RTO endorsement and insurance intimation, and a poor installation is a safety risk. For a new car, factory-fit.
Related calculators
Indian rules, rates and schemes as commonly published for 2025 — state RTO schedules, toll rates, exam statistics and tariffs change frequently. Treat results as planning estimates and confirm with the official source (state transport department, NHAI, NTA, your society bye-laws, your distributor) before relying on them.