Grok 4.5 entered private beta at SpaceX and Tesla on June 28, 2026 with a 1.5-trillion-parameter architecture. xAI claims performance close to or exceeding Claude Opus but neither claim is independently verified — no third party has model access and xAI has not submitted to public benchmarks.
xAI plans to release entirely new foundation models trained from scratch every month through end of 2026. No SWE-bench Verified score exists for Grok 4.5; Claude Code on Opus 4.7 scores 87.6% versus Grok Build’s 70.8% on grok-code-fast-1. The V9-Medium model was projected for mid-June 2026 public release; that window passed without launch.