My certified pre-owned GMC Acadia has a 5 year GM bumper-to-bumper warranty on top of the original factory warranty. I had to pay for it, but the dealer fudged

My certified pre-owned GMC Acadia has a 5 year GM bumper-to-bumper warranty on top of the original factory warranty. I had to pay for it, but the dealer fudged the financing rate to almost 0% to completely cancel it out over the term of the loan, so the loan "interest" is basically paying GM for the warranty rather than the bank.