Elon Musk Rushes Grok 4.5 to the Public as OpenAI Preps GPT

Elon Musk said SpaceXAI will release Grok 4.5 to the public tomorrow. He called it an Opus-class model that runs faster and costs less.

The launch would land around the same time OpenAI moves its GPT-5.6 models toward broad availability.

Grok 4.5 Meets a GPT-5.6 Deadline

Grok 4.5 runs on xAI’s 1.5 trillion-parameter V9 foundation, with Cursor coding data added in supplemental training. It entered private beta at SpaceX and Tesla on June 28.

Musk said at the time that it performs close to or beyond Opus, a claim that rested on early evaluations. Today, he announced that positive feedback from beta customers drove the decision to open Grok 4.5 to the public.

Based on strong positive feedback from customers in our beta test program, @SpaceXAI will make Grok 4.5 available to the public tomorrow.It is an Opus-class model, but faster, more token-efficient and lower cost.

OpenAI also previewed its GPT-5.6 family in late June, but limited access to a small group of vetted partners. On Wednesday, the company said GPT-5.6 Sol, Terra, and Luna will launch publicly on Thursday.

“We’re expanding preview access globally now,” the post read.

The timing revives a long rivalry between Musk and the company he helped start. Musk co-founded OpenAI in 2015 and left the board in 2018.

He then sued OpenAI and Sam Altman in 2024, arguing they had broken an early pledge to run the AI venture as a nonprofit. However, a jury dismissed that lawsuit in May as untimely.

The upcoming launches put the two head-to-head once more. With both companies opening access to their latest flagship models, the focus now shifts from early previews to real-world performance as developers and enterprises begin evaluating the competing systems.

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