First, the data prove that buying a car new and keeping it until it turns 10 is cheaper on average than buying it used and keeping it until it turns 10: https://themakingofamillionaire.com/can-buying-your-next-car-new-actually-save-you-money-6803b8774fe8.

Second, if I can get 0% financing on a car, it's a heck of a lot better than paying 3% for the same car at the same price. Sure, the dealer and carmaker are making a profit anyway. It's just a smaller profit on those paying 0% than on those paying 3%, let alone 5%.