It’s now the default model for AI coding agent Grok Build.
SpaceXAI has launched the first Grok model after its rebranding from xAI and the first one it trained with AI company Cursor. The company says Grok 4.5 is its smartest model yet, built specifically “to excel at coding, agentic tasks and knowledge work.” It was trained across tens of thousands of NVIDIA GB300 GPUs on datasets full of coding, science, engineering and math information.
The model, SpaceX claims, outdoes other leading models at real engineering tasks and is highly proficient at creating functional apps with minimal instructions. In the example above, Grok 4.5 was able to generate an interactive simulation of the solar system with a single prompt. SpaceXAI also says that it was designed to respond faster than “flash” models and to deliver results “at far lower costs.” It’s priced at $2 per million input tokens and $6 per million output tokens. For comparison, OpenAI GPT-5.6’s most powerful variant, Sol, costs $5 per million input tokens and $30 per million output. However, its most affordable variant, Luna, only costs $1 per million input tokens and $6 per million output.
Grok 4.5 is now the default model powering the company’s terminal-based AI coding agent Grok Build, which you can use not just for coding, but also for Excel, PowerPoint and Word tasks. It’s also available from the SpaceXAI console and in all of Cursor’s plans. “We’ve partnered with SpaceXAI to train Grok 4.5,” Cursor announced on X. “It’s our most powerful model yet and the first we’ve built for more than software engineering.”
In April, SpaceXAI and Cursor struck a partnership to develop AI together. The deal could see SpaceXAI either investing $10 billion into Cursor, or acquiring it altogether “later this year” for $60 billion. They have yet to reveal their decision. For now, you can judge whether they work well with each other through Grok 4.5. Take note that you can’t access the model yet if you’re in the European Union, where it’s expected to become available in mid-July.
We’ve partnered with SpaceXAI to train Grok 4.5.
It’s our most powerful model yet and the first we’ve built for more than software engineering. pic.twitter.com/U4B8Tedl34
— Cursor (@cursor_ai) July 8, 2026
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