You can get very close results to GPT 5.5 by using GPT 5.4 with a highly detailed prompt.
I ran a small test to check this properly. I generated the same technical content into summaries using both GPT 5.4 and GPT 5.5, across four different prompt detail levels (Low to XHigh). Then I asked ChatGPT to rank all 8 outputs blindly, without giving it any scoring categories or guidelines โ so my own preferences wouldnโt influence the result.
Hereโs how it turned out:
Rankings (1 = best): GPT 5.5 XHigh โ 9.4/10
Best overall balance of technical depth, accuracy, and framing.
GPT 5.4 XHigh โ 9.0/10
Extremely close to the top. Clean, well-structured, and strong.
GPT 5.4 High โ 8.7/10
Solid and grounded, with good references to the source material.
GPT 5.5 Medium โ 8.5/10
GPT 5.5 High โ 8.5/10
Both clear and reliable.
GPT 5.5 Low โ 8.3/10
Held up surprisingly well for a lighter prompt.
GPT 5.4 Medium โ 8.0/10
GPT 5.4 Low โ 7.6/10
Main takeaway:
Once you go all-in on prompt detail (XHigh), the performance gap between 5.4 and 5.5 becomes quite small. This gives you a practical, lower-cost option without losing much quality.