GPT-3.5 and Grok 4 Fast don't publish scores on any of the same benchmarks, so there's no direct head-to-head comparison. GPT-3.5 shipped 1006 days before Grok 4 Fast, so benchmark comparisons should account for the intervening progress.

Published specifications for these two models are limited — see each model page for the latest details.

Direct benchmark comparisons are unavailable — GPT-3.5 and Grok 4 Fast don't publish scores on any of the same benchmarks.