The Tata Sierra has become one of the most talked-about SUVs in India, not just for its design or features, but for a surprising headline that went viral:
Tata Sierra Petrol achieves a certified 29.9 kmpl fuel efficiency.
This number sounds unbelievable for a mid-size turbo-petrol SUV. So what exactly happened at NATRAX? Is the figure real? And can buyers expect this mileage on the road?
Here is the complete, accurate, and simplified explanation.
Where the 29.9 kmpl Mileage Came From
The figure is real and comes from a certified efficiency run at the National Automotive Test Tracks (NATRAX), Indore.
Official Test Details
- Tested vehicle: Tata Sierra with the new 1.5L Hyperion turbo-petrol engine
- Test duration: 12 continuous hours
- Distance covered: Approximately 800 km
- Certified fuel efficiency: 29.9 kmpl
- Certified by: India Book of Records
The test was conducted under controlled, professional conditions.
How the Sierra Achieved 29.9 kmpl
The number was achieved because NATRAX tests are designed to measure maximum possible efficiency under ideal circumstances. These include:
- Constant driving speed of about 65–70 km/h
- No traffic or stop-and-go movement
- No frequent braking
- Optimal weather and track conditions
- Experienced test drivers maintaining steady acceleration
These conditions allow the engine to operate in its most efficient range for long durations.
Top Speed Achieved at NATRAX vs Customer Model
During the same testing program, the Sierra also demonstrated its performance potential.
Test Track Top Speed
- Achieved: 222 km/h
(Only possible on closed proving grounds)
Production Vehicle Top Speed
- Expected to be limited to approximately 190 km/h
(Electronically restricted for safety and tyre compliance)
What Mileage Customers Should Actually Expect
While the 29.9 kmpl figure is officially certified, real-world results will be much lower due to traffic, braking, varying speeds, inclines, weather, and air-conditioning usage.
Expected Real-World Mileage (Petrol Variants)
1.5L Hyperion Turbo Petrol
- City: 10–14 kmpl
- Highway: 14–17 kmpl
1.5L Revotron NA Petrol
- City: 10–14 kmpl
- Highway: 15–18 kmpl
These values align with what similar mid-size turbo-petrol SUVs deliver in India.
Why the NATRAX Result Still Matters
Although it does not represent real-world usage, the 29.9 kmpl result is still significant because it highlights:
- High combustion efficiency of the Hyperion engine
- Improvements in Tata’s overall engine technology
- Strong aerodynamic and mechanical optimization
- The potential of Tata’s new powertrain platform
It is a technical demonstration of what the engine can achieve under optimal conditions.
Tata Sierra Booking and Delivery Timeline
Tata Motors is preparing for a strong rollout for the Sierra. The expected dates are:
- Booking Start Date: 15 December 2025
- Customer Deliveries Begin: Mid-January 2026 onward
These timelines may vary based on demand and variant availability.
Conclusion
The Tata Sierra’s certified 29.9 kmpl mileage is a genuine achievement recorded at NATRAX under ideal testing conditions. However, it should not be mistaken for daily driving fuel economy. Real-world figures will be significantly lower, but still competitive for a mid-size petrol SUV.
With bookings starting on 15 December 2025 and deliveries expected from mid-January 2026, the Sierra is set to be one of the most talked-about SUVs of the coming year.