This study examines the effects of sustainable reporting in terms of GRI standards and the impact of the corporate sustainability performance of Maruti Suzuki and Tata Motors, two automobile sector giants in India. Sustainable reporting has drawn a lot of attention to inform stakeholders of their environmental, social, and governance (ESG) efforts. This study aims to determine how such reporting affects Maruti Suzuki's and Tata Motors' sustainability performance by thoroughly analysing both companies’ sustainability reporting practices. The study uses a mixed-methods approach, combining qualitative evaluation of the content and transparency of their sustainability reports with quantitative metrics of key performance indicators as per the GRI framework. The findings provide valuable insights into best practices and potential areas for improvement in the relationship between sustainable reporting and corporate sustainability performance in the context of the automobile sector. This study contributes to the academic literature as well as practical decision-making by emphasizing the importance of transparent and comprehensive sustainable reporting in improving corporate sustainability outcomes.