Elon Musk's xAI Starts Private Testing of Grok 4.5 at SpaceX, Tesla

xAI announced that its new large‑language model Grok 4.5, built on a 1.5‑trillion‑parameter V9 foundation and further trained with data from the Cursor coding assistant, has entered private beta testing inside SpaceX and Tesla. Elon Musk posted on X: “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.”

Musk added that reinforcement learning continues to improve the model and that the internal “Grok Build” coding harness is being refined daily. He also said xAI intends to launch a completely new AI model from scratch each month for the remainder of the year. The model follows Grok 4, which used a 0.5‑trillion‑parameter V8‑small base, marking a three‑fold increase in scale. While the public release was slated for May 2026, it has been delayed by about a month.

Separate reports note that a large share of early Grok interactions were for adult‑content generation, raising concerns about commercial viability and prompting internal reviews of moderation tools.