Marketing gimmick. You still pay interest, it is rolled into your final price. Hence the cash discount if you don't go the 0% route, they subtract the interest from the final price. Usually 0% financing allows people who cannot make a large down payment or pay cash for something to buy on credit. But sometimes the cash discount is so small that 0% makes better financial sense. When I bought our Kubota RTV-X I had the option of $300 cash discount or 0% for 48 months. The $15,000 I would have paid for the cash discount makes me $600/yr in interest, so I opted for the 0% financing and left my money in the bank. I don't mind using other people's money if it makes me money.