Elon Musk announces Grok 4.5 private beta, claims performance rivals Anthropic's Opus model

xAI's Grok 4.5 Model Enters Private Beta Testing at SpaceX and Tesla

Elon Musk announced on Saturday that xAI's newest AI model, Grok 4.5, has entered private beta testing at SpaceX and Tesla, marking a significant step in the company's effort to compete with leading AI developers 1

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. The model is built on a 1.5 trillion parameter V9 foundation model, with supplemental Cursor data incorporated during training to enhance its capabilities 3

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. According to Musk's post on X, early internal evaluations show performance near or above Anthropic's Opus model, positioning Grok 4.5 as a potential competitor to one of the industry's leading AI systems 1

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Enhanced Coding Performance Through Cursor Data Integration

The supplemental Cursor data used to train the V9 foundation model came from developer workflows, multi-file edits, refactors, and iterative correction cycles, which xAI has positioned as a strategic way to sharpen the model's coding performance 1

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. Cursor is the AI coding assistant that SpaceX agreed to acquire earlier in June through a $60 billion all-stock deal with Anysphere, the startup behind the popular tool 1

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. The acquisition gives xAI, which SpaceX acquired in February, a stronger foothold in coding—one of the first areas where companies have successfully turned AI into a revenue source from businesses 1

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Reinforcement Learning and Continuous Model Refinement

Musk stated that reinforcement learning continues to improve the model substantially, while "Grok Build," xAI's coding-agent harness, is being refined daily 1

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. He framed the private beta testing at SpaceX and Tesla as an internal proving ground before any wider release, suggesting the companies will serve as real-world testing environments for the AI model 1

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. In an ambitious development timeline, Musk announced that SpaceX will ship a completely new model, trained from scratch, every month for the rest of the year .

Claims of Beating Claude Opus AI Remain Unverified

The claim that xAI's Grok 4.5 model beats Claude Opus AI comes from Musk's own account of internal evaluations, and no third-party benchmark results have been published to verify these assertions 1

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. The release comes as AI companies continue to roll out increasingly capable models, with firms racing to improve reasoning, coding, and conversational abilities while attracting enterprise customers 2

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. Grok 4.5 marks the latest entry in a model line that's been difficult to track even for close observers, as xAI's V9-Medium model was first announced by Elon Musk in late May, with speculation about whether it would ship as "Grok 5" or an interim 4.x release 1

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. The $60 billion Cursor acquisition positions xAI to compete more directly with market leaders Anthropic and OpenAI in the lucrative enterprise AI tools market, particularly in coding automation 1

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