Even if you can afford to pay it in full, if you have a cheap loan available where the interest payment is less than the after-tax interest you would otherwise

Even if you can afford to pay it in full, if you have a cheap loan available where the interest payment is less than the after-tax interest you would otherwise accrue on it (as an investment of some sort) then overall you might come ahead on the deal by taking the loan. This may be true even if you don’t invest it per se but use it to pay off debt at a higher interest rate. Since a car loan is secured against the car itself often it will have a lower interest rate than credit cards for example.