Background

With fuel prices on the rise and a growing focus on sustainable mobility, Compressed Natural Gas (CNG) vehicles have emerged as a compelling alternative for Indian consumers. However, conventional single-cylinder CNG configurations often reduce boot space and face challenges in meeting updated safety regulations and customer expectations.

To address these limitations and enhance market competitiveness, a leading Indian automotive OEM engaged Tata Elxsi to develop factory-fitted twin-cylinder CNG variants for its hatchback and compact SUV models—built on existing ICE platforms and aligned with evolving regulatory and user requirements.

Challenge

The development called for multiple engineering constraints:

• Boot Space Optimization: Integrating a twin-cylinder CNG system without compromising usable boot space.
• Spare Wheel Accessibility: Reconfiguring the underbody to retain spare wheel access alongside the CNG system.
• Safety Compliance: Ensuring adherence to six-airbag requirements and Bharat NCAP crash safety norms, necessitating critical structural reinforcements.
• Component Development: Designing and validating of over 200 new components within a 13-month compressed development cycle.
• System Performance: Achieving targets for crash safety, NVH, and long-term durability under accelerated timelines.

Solution

Tata Elxsi took complete ownership of the program, managing the end-to-end development journey—from concept design to Start of Production (SOP)—within an aggressive 13-month timeline.

Key highlights of the solution included:

• Underbody Redesign: A custom cradle structure was designed to safely house twin CNG cylinders beneath a flat load floor, maintaining usable boot space. A winch-based mechanism ensured easy spare wheel access despite the new packaging constraints.
• Structural Enhancements for Safety Compliance:
  • B-pillar reinforcements
  • Roof rail strengthening
  • Airbag deployment zone optimization:
    Enabled seamless integration of six airbags and ensured compliance with Bharat NCAP crash safety norms.
• Integrated System Design:
  • Dual fuel fillers for CNG and petrol
  • Custom trims and Modified tow hook designs
  • Sealing solutions to prevent water ingress along CNG pipelines routed through wheel arches and floor panels.
• Component Validation & Manufacturability:
  • Over 200 new components underwent forming analysis for manufacturability.
  • Comprehensive validation included CAE simulations, crash testing, NVH tuning, and durability assessments.
• Program Governance & Collaboration

Impact

The twin-cylinder bi-fuel variants were successfully launched in mid-2023, setting a new benchmark in the CNG vehicle segment by offering:

• Optimised Boot Space: One of the most spacious CNG configurations in the segment, addressing a key consumer pain point.
• Seamless User Experience: The twin-cylinder layout enabled intuitive usability and easy refueling through dual fuel fillers.
• Full Safety Compliance: Achieved six-airbag integration and met Bharat NCAP safety standards, ensuring passenger protection without compromising design.
• OEM-Grade Refinement: The factory-fitted CNG variants matched the performance, crashworthiness, and NVH refinement of their petrol-only counterparts.
• Efficient Execution: Tata Elxsi’s integrated engineering approach, covering everything from platform conversion to validation, enabled on-time delivery under a compressed 13-month timeline—demonstrating strong program management and cross-functional agility.

Where are we now

Following the successful rollout of the CNG hatchback and compact SUV models, the OEM has entrusted Tata Elxsi with extended responsibilities for Body & Trim engineering across its broader CNG vehicle portfolio. The vehicles are now in steady production and have gained strong traction in the market. This continued engagement reflects Tata Elxsi’s role as a strategic partner in enabling scalable, regulation-compliant alternate fuel mobility solutions.