OpenAI's GPT-5.6 family dropped this week, and Artificial Analysis has the benchmarks. The headline: GPT-5.6 Sol (max) scores 59 on the Artificial Analysis Intelligence Index — one point below Claude Fable 5 — at approximately one third of the cost.
"GPT-5.6 Sol costs $1.04 per task in the Artificial Analysis Intelligence Index — offering a similar level of intelligence to Claude Fable 5 at approximately one third of the cost."
That's not a minor efficiency bump. It's a meaningful shift in the cost/intelligence curve.
What actually changed
Three-tier family: Sol, Terra, and Luna. Sol is the flagship; Terra (~50% cheaper than Sol) and Luna (~80% cheaper) trade down on intelligence but stay on the Pareto frontier ahead of GPT-5.5 at every effort level.
