This thesis explores how sustainability is communicated through social media in the automotive industry. The research focuses on three companies: Tesla, BYD, and BMW. These brands represent different positions in the transition to sustainable transport. The main goal of the study is to understand how these companies use digital platforms to present their environmental commitment, build credibility, and engage audiences. The research is based on a qualitative comparative analysis of official communication on Instagram, LinkedIn, YouTube, Facebook, X, and TikTok, together with information from corporate websites. The study looks at communication style, type of content, platform differences, and audience reactions such as likes, comments, and engagement levels.