Prototyping in JS

gistfile1.js

<script type="text/javascript" charset="utf-8">
  function Car (carMake,carModel,carYear) {
    this.make = carMake;
    this.model = carModel;
    this.year = carYear;
  };
  Car.prototype = {
    startEngine : function(){console.log("engine started")},
    stopEngine : function(){console.log("engine stopped")},
    sayMake : function(){console.log(this.make)},
    sayModel : function () {console.log(this.model)},
    sayYear : function () {console.log(this.year)}
  }
  var myCar = new Car("Toyota","Matrix","2003");
  myCar.sayMake();
  myCar.sayModel();
  myCar.sayYear();
  myCar.startEngine();
  myCar.stopEngine();
</script>