Can a bank repossess a car before the last day of payment?

Unless it's explicitly stated in the fine print that they can't do any such thing, they have a right to repossess the moment the payment is rendered late, if they so wish. However, if you have documentation from the bank showing them explicitly giving you a deadline date, and they come to repossess before then, you may have grounds for a lawsuit. However, you would need to find out if it was the bank which had your car repossessed on that particular day, or if it was the repossessors jumping the gun and going forth with it before the date which they were specified to take possession of the vehicle.