If it is stated in your lease that you have an entrance and driveway IT MUST BE HONORED by the landlord. If it is not it is a complete breaking of contract. I know that the neighbor does not have the same exact contract as you but what you and the landlord signed stands. If the landlord granted both of you use of the driveway then the neighbor is gonna have to share. Period. It is unreasonable for a home/apt to have an actual place and driveway for a vehicle and tell the person paying rent and access to that very driveway that no, they can't have it.