On June 28, 2026, Elon Musk announced Grok 4.5 — built on xAI’s 1.5T V9 foundation with Cursor developer data in supplemental training — entered private beta at SpaceX and Tesla. A single owner now controls compute (Colossus), the model (Grok), and the coding tool (Cursor) that feeds training data.
Musk’s “close to, perhaps exceeding Opus” claim is a self-eval with no independent benchmark. The flywheel closes: Cursor usage data flows into model training at companies Musk controls. Everything publicly known traces to Musk’s X post. Treat specifications as vendor-stated. The model most developers can use today remains Grok 4.3, not Grok 4.5.