An ‘Opus-Class’ Model on a New Architecture
Elon Musk described Grok 4.5 as “Opus-class” — a reference to Anthropic’s Claude Opus line — but said it is faster, more token-efficient, and cheaper to operate. The model runs on xAI’s new V9 foundation architecture with roughly 1.5 trillion parameters, about three times the scale of the V8-small architecture that powered earlier Grok 4 variants. felloai.com mashable.com codersera.com
Grok 4.5 entered a private beta with SpaceX and Tesla teams on June 28 and reaches the public 11 days later. SpaceXAI’s own announcement said the model is “built to excel at coding, agentic tasks, and knowledge work”. Early internal benchmarks suggest it performs on par with GPT 5.5 and close to Opus 4.8 on coding tasks, though no independent third-party evaluations have yet been published. codersera.com x.com x.ai threads.com felloai.com
Cursor Data Sharpens Coding Performance
The release is notable as the first Grok model to incorporate training data from Cursor, the AI coding platform that SpaceX agreed to acquire for $60 billion in an all-stock deal announced in June. That transaction, which SpaceX expects to close in the third quarter, would be one of the largest acquisitions of a venture-backed startup on record. cnbc.com news.crunchbase.com digitalapplied.com
Cursor data was folded into supplemental training to sharpen Grok 4.5’s coding and technical capabilities, an area where Anthropic’s Opus models have historically been strongest. The collaboration signals how SpaceXAI intends to leverage the Cursor deal beyond the coding tool itself, feeding real-world developer interaction data back into its foundation models. felloai.com codersera.com
Pricing and Competition
SpaceXAI had not confirmed Grok 4.5 API pricing at the time of announcement. For reference, its predecessor Grok 4.3 was priced at $1.25 per million input tokens and $2.50 per million output tokens. The model will be accessible through the X platform for Premium+ and SuperGrok subscribers and through the xAI developer API. codersera.com felloai.com
The launch comes as competition intensifies among frontier AI labs. Reuters reported Monday that SpaceXAI was planning the release as early as Wednesday, aligning with Axios, which described Grok 4.5 as SpaceXAI’s “first release since going public and acquiring the AI coding startup”. reuters.com axios.com
