Grok 4.5 enters private beta at SpaceX and Tesla

Elon Musk announced on X on 28 June 2026 that xAI's Grok 4.5 had entered private beta at SpaceX and Tesla — the first confirmed deployment of the model inside his companies, ahead of any wider release. It runs on xAI's ninth-generation V9 architecture, which finished pre-training on 26 May 2026 at 1.5 trillion parameters — roughly three times the v8-small model that serves Grok on X and in Tesla today. xAI reportedly added Cursor coding data in supplemental training, pointing to a focus on code and technical reasoning.

Musk claimed early evaluations put Grok 4.5 close to, or above, Anthropic's Claude Opus — but that is an unverified claim. xAI has published no benchmarks and no system card; the only evaluators are SpaceX and Tesla engineers at Musk's own companies; and no independent benchmark such as LMArena, Artificial Analysis or SWE-bench has scored it. For now, the 'beats Opus' line is a claim, not a measured result.

xAI has said it plans to release a new from-scratch foundation model every month through the end of 2026, with monthly V9 variants — 4.5, 4.6, 4.7 — feeding a larger Grok 5 on its Colossus 2 supercluster. Watch for the first version that reaches the public, and whether it ships with benchmark scores attached.

One more caveat worth flagging for readers weighing the hype: a 'private beta' inside the maker's own companies is not the same as a launch, and a founder's word is not the same as a benchmark. Until Grok 4.5 reaches outside developers, or an independent lab publishes a score, treat it as a capability claim in progress — not a model you can yet compare against Claude Opus, buy, or build a product on. The number to wait for is one xAI hasn't published.