Maruti Suzuki’s Diesel Engine Debacle: The Untold Technical Flaws and Strategic Shift

In 2020, Maruti Suzuki abruptly stopped selling diesel cars, leaving many puzzled, especially since the company had invested five years and nearly Rs 1,000 crore in developing a new diesel engine. The official reason cited was the dwindling market for diesel cars due to stringent BS6 emission norms and a narrower price gap between petrol and diesel fuels. However, this explanation doesn’t fully address why Maruti would invest so heavily only to withdraw shortly after.

The Backstory

Maruti Suzuki’s decision to develop its own diesel engine was driven by the desire to reduce dependency on Fiat’s 1.3 DDiS diesel engine, which had become costly to upgrade to BS6 norms. The new in-house 1.5-liter turbo-diesel engine, the E15A, was intended to replace the Fiat engine and power several models, including the Ciaz and Ertiga. The E15A debuted in the Ciaz in 2019 and was praised for its performance and refinement, indicating a promising future for Maruti’s diesel lineup.

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The Technical Flaw

The crux of the issue with the E15A lay in its cylinder head, which featured an integrated exhaust manifold. While this design is advantageous in petrol engines, offering better packaging and improved fuel efficiency, it proved problematic for diesels. Diesel engines run cooler than petrol engines, and the integrated manifold caused the exhaust gases to overcool. This became a significant problem when trying to meet BS6 emission standards, which require a Diesel Particulate Filter (DPF) to trap soot and other particulates.

The BS6 Challenge

For BS6 compliance, the DPF needs to reach high temperatures to burn off trapped particulates. However, the E15A’s overcooled exhaust gases caused hydrocarbons to condense into liquid form, clogging the DPF and preventing effective filtration. During regeneration, when the DPF is heated to burn off soot, the trapped liquid hydrocarbons could cause temperatures to spike to damaging levels, potentially cracking the DPF and DOC (Diesel Oxidation Catalyst).

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The Consequence

Maruti Suzuki’s engineers faced insurmountable challenges in making the E15A BS6-compliant. Despite initially showing potential, the engine’s fundamental design flaw meant it couldn’t be upgraded cost-effectively. Redesigning the cylinder head to use a conventional exhaust manifold would have required significant additional investment, which, combined with the declining market for diesel cars and the shift towards electrification, made it unfeasible.

Strategic Shift

Maruti Suzuki has since pivoted to a multi-fuel strategy, focusing on CNG, hybrids, EVs, and biofuels. This shift is partly why the company has managed to maintain a strong market presence despite the exit from diesel. However, the lack of diesel options has impacted sales in certain segments, such as SUVs, where diesel remains popular. The Jimny, for example, has struggled in the market due to the absence of a diesel variant.

Maruti Suzuki’s exit from diesel was driven by a combination of technical challenges and strategic realignment towards future-ready powertrains.