I think he's implying that his boycott imposed a cost on him, and therefore had more meaning, because had they behaved differently, he would have liked to have owned a Nissan.
Which is severely undermined by the claim that Nissan makes great cars
Especially when considering the person making the claim has an implied incentive to hate the cars. He's making a genuine claim that "I want to hate their cars but I cant"
which is fantastic advertising for Nissan.