While we wait for a general release, the system card is the best hint as to what is going on with the new candidate for America's Next Top Model, GPT-5.6.

This is only an OpenAI model card, so by my standards it's a light read. There's a lot of things that you get in an Anthropic card, that are missing in an OpenAI card.

Overall, the card gives a clear and consistent impression that GPT-5.6-Sol is a substantial improvement over GPT-5.5, but still short of Mythos.

OpenAI calls it a ‘step function better’ than GPT-5.5. That seems accurate.

OpenAI: Sol is our new flagship and a step function better than GPT-5.5.
Terra delivers performance competitive to GPT-5.5 at 2x lower cost.
Luna is our most cost-efficient model, delivering strong capability at our lowest cost.