Elon Musk's AI operation picked a pointed moment to ship. SpaceXAI — the former xAI, now a segment of the newly public SpaceX — announced Grok 4.5 on July 8 and said it would reach the public the next day, one day before OpenAI's GPT-5.6 rollout. Musk's pitch: "It is an Opus-class model, but faster, more token-efficient and lower cost."

The claim

By SpaceXAI's own framing, Grok 4.5 is "roughly comparable to Opus 4.7" — Anthropic's model, not the newer Opus 4.8 — "but much faster." That is a deliberate position: compete on the combination of capability, speed and price rather than topping the charts. The model is described as a 1.5-trillion-parameter mixture-of-experts built on xAI's "V9" foundation, with a 500,000-token context window Musk suggested could reach 1 million "by next week."

Price is the weapon

API access lists at $2 per million input tokens and $6 per million output, with cached input at $0.50 — steeply below Opus 4.7 ($5/$25) and GPT-5.6 Sol ($5/$30), and matched against OpenAI's budget Luna ($1/$6). Grok 4.5 went live day one across Grok Build, Cursor (double usage for the first week), the SpaceXAI API, OpenRouter, Vercel, Cloudflare, Snowflake and Databricks. The EU is expected to follow in mid-July.

The scoreboard

Vendor numbers put Grok 4.5 at 83.3% on Terminal-Bench 2.1 and 64.7% on SWE-Bench Pro, with a headline efficiency claim of 4.2x fewer output tokens than Opus 4.8 on that coding test. Independent testing by Artificial Analysis ranked it fourth on its Intelligence Index at a score of 54 — behind Anthropic's Fable 5 (60), Opus 4.8 (56) and GPT-5.5 (55), but first on a banking-agent benchmark. The consistent read across reviewers: strong, cost-efficient, just short of best-in-class. The model was trained alongside Cursor on tens of thousands of Nvidia GB300 GPUs and reinforcement-learned over hundreds of thousands of software-engineering tasks.

Behind the rebrand

Grok 4.5 is the first model since SpaceX absorbed xAI in a February all-stock deal that valued the AI unit at $250 billion, and since SpaceX's record $75 billion June IPO at $135 a share. The positioning — Excel models, slide decks, agentic coding — tilts toward knowledge work over consumer chat, aimed squarely at the enterprise budgets OpenAI and Anthropic are chasing.