Hide value with private access modifier in PHP

<?php/*from w  ww . j a  v a  2 s .c o  m*/

class Car {
  public $color;
  public $manufacturer;
  public $model;
  private $_speed = 0;

  public function accelerate() {
    if ( $this->_speed >= 100 ) return false;
    $this->_speed += 10;
    return true;
  }

  public function brake() {
    if ( $this->_speed <= 0 ) return false;
    $this->_speed -= 10;
    return true;
  }

  public function getSpeed() {
    return $this->_speed;
  }

}

$myCar = new Car();
$myCar->color = "red";
$myCar->manufacturer = "Volkswagen";
$myCar->model = "Beetle";

echo "<p>I'm driving a $myCar->color $myCar->manufacturer $myCar->model.</p>";
while ( $myCar->accelerate() ) {
  echo "Current speed: " . $myCar->getSpeed() . " mph<br />";
}

while ( $myCar->brake() ) {
  echo "Current speed: " . $myCar->getSpeed() . " mph<br />";
}


?>