So I ran your scenario 2 ways. paying the 17% card first or paying the car off & the balance to the card. Either way, it will take 6 months to pay both off fully. But if you pay $7000 on the card now, you will pay only $45 in interest over those 6 months vs if you pay off the car & pay down the card to $3400, you will pay $170 in interest. There’s no benefit to paying down the 0% interest card first because it won’t make the other payoffs happen faster & you’ll pay way more in interest. And after the 6 months, make sure you put those payments from the paid off card & your car to the 0% card. You say it’s 0% interest for 18 months but at $362/month, it will take 21 months to pay off so you’ll get hit with some interest in the end if you don’t.