[Musk: Grok 4.5 Enters Private Testing at SpaceX and Tesla, Performance May Rival or Surpass Opus] Musk posted on the X platform that Grok 4.5, built on the 1.5T V9 f foundational model, has entered private testing within SpaceX and Tesla, with Cursor data incorporated into supplementary training. Early evaluations indicate that the model's performance has approached or may even surpass the level of Opus. Musk also noted that reinforcement learning (RL) continues to significantly enhance the model's capabilities, while the Grok Build training framework is undergoing continuous iterative optimization. Additionally, Musk revealed that a new model, fully trained from scratch by SpaceX, will be released on a monthly basis throughout the remainder of this year.