Real CNG Mileage in India — Claimed vs Actual (2026 Data)

The claimed vs real mileage gap

Every CNG car in India advertises an ARAI-certified mileage figure. These tests are done in lab conditions: gentle acceleration, no AC, flat roads, optimal tire pressure.

Real-world driving is nothing like that. You idle in traffic, blast the AC, accelerate hard, and drive on potholed roads. The result: real mileage is typically 85-90% of claimed mileage for factory CNG cars, and 70-80% for poorly-tuned aftermarket CNG kits.

This guide gives you the real numbers based on owner reports and our own testing.

Real-world CNG mileage: Popular cars

Maruti Suzuki Wagon R CNG (1.2L)

ARAI claimed: 34.05 km/kg
Real-world city: 28-30 km/kg
Real-world highway: 32-35 km/kg
Efficiency vs claimed: 85-90%

Why it performs well:
The Wagon R's 1.2L engine is well-tuned for CNG. Maruti's latest CNG kits have minimal power loss compared to petrol mode. Light body weight helps efficiency.

Owner feedback:
"I get 30-31 km/kg in Bangalore traffic with AC on. On the highway to Mysore, I touched 34 km/kg at 80-90 km/h." — Rajesh K., Wagon R owner (2024 model)

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Maruti Suzuki Celerio CNG (1.0L)

ARAI claimed: 35.60 km/kg
Real-world city: 29-31 km/kg
Real-world highway: 33-36 km/kg
Efficiency vs claimed: 85-90%

Why it performs well:
The Celerio is the lightest CNG car in India. The 1.0L engine is small but efficient. Low aerodynamic drag helps highway mileage.

Owner feedback:
"I drive 50 km daily in Delhi NCR traffic. I average 29-30 km/kg with full AC. On weekend highway trips, I get 34+ easily." — Amit S., Celerio owner (2023 model)

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Maruti Suzuki Ertiga CNG (1.5L)

ARAI claimed: 26.08 km/kg
Real-world city: 21-23 km/kg
Real-world highway: 24-27 km/kg
Efficiency vs claimed: 80-85%

Why it performs worse:
The Ertiga is a 7-seater MPV — it is heavier and has more frontal area than hatchbacks. The 1.5L engine works harder, especially with a full load of passengers and luggage.

Owner feedback:
"With 5-6 people on board, I get 21-22 km/kg in city. On highways with just me and my wife, I get 25-26 km/kg." — Suresh M., Ertiga owner (2023 model)

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Tata Tiago iCNG (1.2L)

ARAI claimed: 26.49 km/kg
Real-world city: 22-24 km/kg
Real-world highway: 25-27 km/kg
Efficiency vs claimed: 85-90%

Why it performs decent:
Tata's iCNG tech has good engine tuning. The car automatically switches to petrol if CNG runs out, so owners do not baby the throttle.

Owner feedback:
"I get 23-24 km/kg in Mumbai traffic. Highway mileage is 26+ consistently. The auto-switch to petrol gives peace of mind." — Priya D., Tiago iCNG owner (2024 model)

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Hyundai Grand i10 Nios CNG (1.2L)

ARAI claimed: 27.70 km/kg
Real-world city: 23-25 km/kg
Real-world highway: 26-28 km/kg
Efficiency vs claimed: 85-90%

Why it performs decent:
Hyundai's CNG system is refined and well-integrated. The engine is smooth, which helps efficiency.

Owner feedback:
"I drive in Hyderabad city traffic. I get 24 km/kg average with moderate AC use. Highway trips give me 27-28 km/kg." — Karthik R., Grand i10 Nios CNG owner (2023 model)

City vs highway: Which is better for CNG?

Highway driving gives 10-15% better mileage than city driving — just like petrol or diesel.

Why highway is better:

• No idling in traffic (idling consumes fuel with zero km traveled)
• Steady speeds (50-80 km/h is the sweet spot for CNG efficiency)
• Less acceleration/braking (smooth driving saves fuel)

Why city is worse:

• Frequent stop-and-go traffic
• AC runs continuously (AC is a bigger drain at low speeds)
• More time idling at signals

But CNG still beats petrol in both conditions. A petrol car doing 12 km/l city becomes 15 km/l highway (25% improvement). A CNG car doing 28 km/kg city becomes 33 km/kg highway (18% improvement).

Factors that kill CNG mileage

1. Aggressive driving

Hard acceleration drains the CNG tank fast. Smooth, gradual acceleration improves mileage by 10-15%.

Tip: Accelerate gently up to 40-50 km/h, then maintain speed. Avoid flooring the throttle from every traffic light.

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2. AC overuse

AC in CNG cars is powered by the engine, just like petrol cars. Full-blast AC reduces mileage by 10-15% in city driving.

Tip: Set AC to 24-25°C instead of 18°C. Use the fan on lower settings. Once the cabin cools, the AC compressor cycles off, using less power.

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3. Under-inflated tires

Low tire pressure increases rolling resistance. Check tire pressure monthly. Maintain 32-35 PSI (check your car's manual for exact specs).

Mileage loss from under-inflated tires: 5-10%

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4. Excess weight

Every 50 kg of extra weight reduces mileage by 1-2%. Remove unnecessary items from the boot. Do not carry a full CNG tank + full petrol tank unless you need the range.

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5. Poor maintenance

CNG air filters clog faster than petrol filters because CNG combustion produces more carbon deposits. Change the air filter every 10,000-15,000 km.

Also check:

• CNG kit leaks (smell of gas near the tank or engine)
• Spark plugs (replace every 20,000-30,000 km)
• Engine oil (use manufacturer-recommended grade)

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6. Aftermarket CNG kit quality

Aftermarket CNG kits vary wildly in quality. A cheap kit with poor tuning can reduce mileage by 15-20% compared to factory CNG.

If you have an aftermarket kit:

• Get it tuned by a certified installer every 20,000 km
• Check for gas leaks regularly (leaks waste CNG)
• Ensure the ECU map is optimized for CNG

How to maximize CNG mileage

1. Drive in the 50-80 km/h sweet spot
CNG engines are most efficient at 50-80 km/h. Faster speeds (100+ km/h) increase aerodynamic drag. Slower speeds (below 40 km/h) waste fuel in low gears.

2. Anticipate traffic and coast
Lift off the throttle early when approaching a red light or slow traffic. Let the car coast instead of braking hard.

3. Use petrol for cold starts
CNG burns less efficiently when the engine is cold. Start on petrol, drive for 2-3 minutes, then switch to CNG once the engine warms up.

4. Keep the CNG tank full
A nearly empty CNG tank reduces pressure, which affects combustion efficiency. Fill up when you hit 25-30% remaining.

5. Service regularly
Follow the manufacturer's service schedule. Clean or replace air filters, check spark plugs, and ensure the CNG kit is leak-free.

Real-world fuel cost comparison

Let's compare the cost per km for CNG vs petrol:

Car	Fuel	Mileage	Fuel price	Cost per km
Wagon R	Petrol	18 km/l	₹100/L	₹5.55
Wagon R	CNG	30 km/kg	₹55/kg	₹1.83
Savings with CNG	—	—	—	₹3.72 per km

At 1,000 km per month, CNG saves ₹3,720 per month compared to petrol.

Over 5 years (60,000 km), that is ₹2,23,200 saved.

The verdict

Best real-world CNG mileage: Maruti Celerio CNG (33-36 km/kg highway)
Best for families: Maruti Wagon R CNG (30-35 km/kg, spacious)
Best 7-seater: Maruti Ertiga CNG (24-27 km/kg, still better than petrol MPVs)

Most factory CNG cars deliver 85-90% of claimed mileage in real-world conditions. If you are getting less than 80%, something is wrong — poor maintenance, kit leaks, or driving style.

CNG mileage is 10-15% better on highways than in the city, but even city mileage is 60-70% cheaper than petrol. If you drive 1,000+ km per month, CNG pays for itself within 12-18 months.