function Vehicle() {
    this.speed = 20;
}

Vehicle.prototype.isFasterThan = function(other) {
    return this.speed > other.speed;
};

function Car() {
    Vehicle.call(this);
    this.color = 'red';
}

Car.prototype = Object.create(Vehicle.prototype);

Car.prototype.drive = function(speed) {
    this.speed = speed;
};