Making a higher down payment will mean that you will need to avail a lower loan amount to buy a car. When you avail a lower loan amount, there are chances that banks or lenders may offer you a car loan at lower interest rates. This is simply because if the loan amount is lower, the repayment will be quicker. So, though there is no hard and fast rule to how much down payment you should make, a higher down payment will ensure that your debt liability is lesser.