xAI’s Grok 4.5, announced on June 28 via Elon Musk’s X account, has entered a private beta testing phase exclusively with teams at SpaceX and Tesla. The model is built on xAI’s new V9 foundation, which packs 1.5 trillion parameters, making it roughly three times larger than the V8-small architecture that powered earlier Grok 4 variants. xAI supplemented its training pipeline with Cursor data to sharpen coding and technical competencies. Early internal evaluations suggest Grok 4.5’s performance is comparable to, if not superior to, Anthropic’s Claude Opus. Musk has referenced advancements tied to reinforcement learning features and the Grok Build system. Real-world applications inside SpaceX and Tesla are reportedly feeding back beneficial improvements. xAI has not specified a public release date for Grok 4.5; the original timeline had pegged the model for a late May 2026 launch, meaning it’s already running behind schedule by about a month. Grok 4 itself only launched in July 2025. xAI’s roadmap includes monthly model releases throughout 2026, with variants of Grok 5 projected to reach 10 trillion parameters.