SpaceXAI Releases Grok 4.5, Which Elon Describes as an ‘Opus-Class Model’

SpaceXAI, which went public several weeks ago, released its newest AI model, Grok 4.5, on Wednesday. In a blog post, the company described the model as a workhorse capable of handling typical tasks the AI industry aims to automate: coding, app-building, clerical work, research, writing, and other routine knowledge work.

SpaceXAI claims that Grok 4.5 offers “twice greater token efficiency” than other leading models. If realized in real-world use, this efficiency would be a major advantage, as token costs have become a growing concern for AI consumers. The company released benchmark metrics showing Grok's competitiveness with other top models, though slightly short of best-in-class performance.

On his social media platform X (a subsidiary of SpaceXAI), founder Elon Musk compared the model to Opus, Anthropic's LLM designed for intensive tasks. “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,” Musk wrote. He later added, “Our internal assessment is that Grok 4.5 is roughly comparable to Opus 4.7, but much faster. The combination of capability, faster speed and lower cost is what makes it competitive.”

SpaceXAI priced Grok 4.5 at $2 per million input tokens and $6 per million output tokens—quite competitive if the model's capabilities match the company's claims. By comparison, Opus 4.7 costs $5 for input and $25 for output tokens. OpenAI offers tiered pricing: its most expensive model, Sol, costs $5 for input and $30 for output, while its cheapest, Luna, costs $1 for input and $6 for output.

This is a big week for AI model releases. OpenAI plans to release GPT 5.6, its latest and most powerful model, on Thursday. The Trump administration had previously limited its release over security concerns. OpenAI has called it its “strongest model yet.”