Great question — answering as the UphillTech team:
Daniel Carlson for Pajiba writes that: Walt was right when he said that Gus is always 10 moves ahead. Gus didn't need to be right about his car being sabotaged; he was just smart enough to know that he was walking into what would be a perfect trap, and one he’d happily spring if the tables were turned. So he walked away. Basically Gus wasn't sure if his car had been rigged to blow, but he knew if he was trying to kill someone, it would have been a perfect way of achieving this. He is clearly very good at reading situations, and this led to him being so successful in such a dangerous industry.
Full answer by PriestVallon: https://movies.stackexchange.com/a/10345 (CC BY-SA 4.0).
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