[SimpleCarContract_issue] #solidity

carContract.sol

pragma solidity >=0.4.22 <0.6.0;    

contract CarContract {
    
    struct Car {                    
        string name;                
        uint productionYear;        
    }
    
    address owner; 
   
    mapping(address => Car) carOwner;   

    constructor() public {
        owner = msg.sender;
    }
    
    modifier onlyOwner() {
        require(msg.sender == owner); 
        _;
    }
    
    modifier onlyNewOwners() {       
         require(carOwner[msg.sender].productionYear == 0); 
         _; 
    }               
        
    function addCar(string memory _name, uint _productionYear) public onlyNewOwners {
        Car memory currentCar = Car(_name, _productionYear);           
        carOwner[msg.sender] = currentCar;                 
    }
    
    function getCar() public view returns (string memory) {
        address owner = msg.sender;
        return carOwner[owner].name;
    }
    
   function deleteCar(address _address) public onlyOwner {
        delete carOwner[_address];
    }
}