SpaceXAI released Grok 4.5 this week, a new artificial intelligence model designed for coding, agentic tasks, and knowledge work. The company stated that Grok 4.5 is its smartest model to date and was trained in conjunction with Cursor, an AI-powered coding editor. This collaboration suggests a focus on enhancing developer productivity and complex problem-solving capabilities. Grok 4.5 demonstrates significant improvements in token efficiency, reportedly using approximately 4.2 times fewer output tokens than Opus 4.8 on the SWE Bench Pro benchmark. The model is priced at $2 per million input tokens and $6 per million output tokens, with a serving speed of 80 tokens per second. SpaceXAI also highlighted Grok 4.5's #1 ranking on Harvey’s Legal Agent Benchmark, indicating its strength in office-related tasks and legal applications. It is now the default model within the Grok Build environment. SpaceXAI trained Grok 4.5 on extensive datasets covering coding, science, engineering, and mathematics, utilizing tens of thousands of NVIDIA GB300 GPUs. The training process incorporated advanced techniques for large-scale runs, including rigorous data filtering, deduplication, quality scoring, and domain-specific selection. Reinforcement learning was scaled to hundreds of thousands of tasks, with a particular emphasis on multi-step software engineering and technical problem-solving. The training stack supports highly asynchronous operations, allowing agentic rollouts to continue learning for extended periods. Benchmark performance data released by SpaceXAI shows Grok 4.5 performing competitively against leading models. While the company's internal charts indicate that Fable (max) achieved the highest scores across four coding benchmarks, Grok 4.5 was noted as being the closest competitor on the Terminal Bench 2.1. The model's reasoning capabilities are described as both intelligent and efficient, positioning it as a powerful tool for specialized engineering and knowledge-intensive work.