Elon Musk has announced that Grok 4.5 entered private beta testing on Sunday. The new model is being trialed at his companies SpaceX and Tesla. The reveal marks the latest step in Musk’s fast-moving AI push.
Grok 4.5 sits on a large new foundation, according to Musk. He said it is built on a 1.5-trillion-parameter V9 foundation model. The training also incorporated Cursor data during a supplemental phase. Those details point to a heavier, more capable system than before.
Musk made bold claims about the model’s early performance. He said initial evaluations approach or potentially surpass Opus. That comparison places Grok 4.5 against one of the leading rival AI models. Opus is made by Anthropic, a top competitor in the AI race.
Grok 4.5, based on our 1.5T V9 foundation model, with Cursor data added in supplemental training, is now in private beta at SpaceX & Tesla. Early evals show performance close to, perhaps exceeding Opus.
RL is continuing to significantly improve the model, and the Grok Build…
— Elon Musk (@elonmusk) June 28, 2026
He also stressed that the model keeps improving rapidly. Reinforcement learning continues to boost performance substantially, Musk said. The Grok Build harness advances daily, according to his account. Those gains suggest the beta is still early and evolving.
The announcement came with an aggressive release roadmap. SpaceX plans to release completely new models throughout this year. Musk said each would be trained from scratch every month. That cadence would far outpace the typical model release cycle.
The claims arrive without independent benchmarks or external testing. Musk shared the update himself rather than through a formal launch. No third party has verified the performance comparisons yet. The private beta also limits access to Musk’s own companies for now.
The move fits Musk’s broader ambition to lead in AI. His ventures have built one of the world’s largest AI training systems. Grok already powers features across his social platform X. A stronger Grok could deepen integration across Tesla, SpaceX, and X. For now, the wider public must wait for a public release.
