India’s First Tata Sierra Converted To CNG Is Here (Video)
Tata Motors launched the all-new Sierra in India in November 2025. The nameplate carries much weight in the Indian context, and the new SUV does justice to the original on many fronts. The launch thus created much buzz online and generated high customer interest. Now, videos of what claims to be India’s first CNG conversion of the new Sierra have surfaced online.
Sai Fuel, a CNG kit specialist from Gujarat’s Vadodara, shared a series of videos showing the different stages of conversion. The donor car here is a Sierra Adventure Plus variant, powered by the 1.5 naturally aspirated petrol (Revotron) engine. This unit makes 106hp and 145 Nm and runs on Atkinson cycle. This SUV has a manual transmission.
A EuropeGAS injection controller was used in this case. Made in Poland, it was chosen as it is compatible with the engine. The video also shows the installation process, and the host mentions that they did not have to cut any wires during the conversion and used proper sockets and connectors.
Cutting and rejoining the car’s wires is not at all recommended during any CNG conversion, as it increases the chances of fire and other electrical failures. Doing so will also void the vehicle’s warranty. The new Sierra comes with a three-year or 1 lakh km warranty.
The team also changed the Engine Control Module (ECM). Two ECMs are reportedly being installed as part of the conversion. In this conversion, the CNG tank is placed in the boot. The Sierra offers a generous boot space of 662litres, measured to the roof. The video doesn’t mention the exact size of the CNG tank(s) being used here. The boot will be able to accommodate it comfortably/. In the video, we can see the CNG lines being installed between the engine bay and boot area.
The Sierra is underpinned by the ARGOS platform. It is a multi-energy architecture and we may see Tata Motors rolling out a CNG version of the SUV in the future. Till then, conversions like this may be able to keep CNG aspirants happy.
The handle has also shared another video that shows the Sierra to have developed some glitches in its sunroof and instrument cluster after the CNG installation. The car’s odometer had just under 100km initially. After installation, it kept showing 99999 km. The sunroof too, reportedly malfunctioned. It remains unclear if these had something to do with the installation. The handle may share more videos explaining this in the future.
The Sierra comes with three engine options- 1.5L naturally aspirated, high compression petrol engine, 1.5L turbocharged petrol, and 1.5 turbocharged diesel. Petrol engines are easier to convert to CNG dual-fuel units, as they are based on spark-ignition principle. This makes retrofitting easier and cost-effective. Diesel engines, on the other hand, are more complex, and conversions can be relatively more expensive.
Choosing the Revotron petrol engine for this conversion was indeed a great idea. It has both merits and demerits, but the user seems to benefit in the larger picture. The 1.5L naturally aspirated petrol engine of new Tata Sierra has a compression ratio of 13:1. It is a high compression, naturally aspirated engine.
High-compression engines are usually the best for CNG conversion. Engines with compression ratios 10.5:1 typically allow for better efficiency and reduced engine knocking with CNG, as the fuel itself has a high octane rating. The only things to keep in mind are to use good-quality conversion kits and ensure proper installation. Aftermarket installations, otherwise, aren’t recommended from a safety perspective. In factory CNG forms, vehicles undergo rigorous safety testing and are put under strict checklists, which may be overlooked in certain aftermarket installations.
On the downside, this petrol engine works based on the Atkinson cycle. Even in its stock form, this engine prioritises efficiency. Compared to an Otto cycle engine, it produces slightly less power and torque. When converted into CNG, there would be a further drop in power. Manufacturers usually couple CNG Atkinson engines with hybrid tech to compensate for these losses.
This engine, in its stock form, takes over 17 seconds to make the vehicle sprint from 0 to 100 kph. That’s slow. The CNG conversion will only make it slower. It will, however, bring about a notable reduction in fuel expenses, even though the shop doesn’t mention anything about how far the SUV would run with a kilogram of CNG.
This isn’t the first time that we have seen people installing aftermarket CNG conversion kits on vehicles that one would hardly expect them to be in. In a previous occurrence, a Thar ROXX owner converted his petrol-powered SUV into CNG. The ROXX’s 2.0L turbocharged petrol engine, though loved for its performance, is notorious for its fuel efficiency.
This may have made the owner turn to CNG. The conversion in this case used a twin-cylinder setup to store CNG- like what you see in certain Tata and Mahindra models. Further details of this conversion aren’t known.