The latest wave of internet-based AI search tools “often make mistakes, misread information and even give risky advice”, according to a damning investigation by Which? .

The Which? team surveyed 4,189 adults in the UK in September 2025 on their AI habits and found that about a third of them believe AI searches are more important to them than standard web searching.

Furthermore, around half of respondents said they trust the information they receive from AI search engines to a “great” or “reasonable” extent, and this rose to two-thirds among frequent users.

The team tested six AI tools: ChatGPT, Google Gemini (both Gemini on its own and Gemini AI overviews, or AIO, in standard Google searches), Microsoft’s Copilot, Meta AI and Perplexity.

Each AI engine was asked 40 common questions

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