From this source:
"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 lead to him being so successful he in such a dangerous industry.