Elon Musk Reveals Grok 4.5 Powered by 1.5 Trillion Parameters, Private Beta Begins at Tesla and SpaceX

Musk said data from the Cursor AI coding assistant was also added to the model’s additional training. It has improved the model’s coding capabilities and ability to solve complex problems, he said.

According to Elon Musk, Grok's reinforcement learning (RL) model is constantly improving. Additionally, daily improvements are being made to the Grok build coding harness to make future models even more capable.

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

Musk stated that xAI plans to launch a completely freshly trained AI model every month via SpaceX for the rest of this year. The public release of the V9-Medium model was originally expected in mid-June, but private testing of Grok 4.5 is now considered the next major step.

Currently, Grok 4.5 is only available in private beta testing within SpaceX and Tesla. The company has not announced a public release date. Furthermore, independent benchmark results have not yet been released, so actual performance can only be assessed after extensive testing.