javascript not used..try it..!!
<form method="post">
<div id="dropdown">
<?php
if(isset($_POST['cars']))
{
$mycar=$_POST['cars'];
}
else
{
$mycar='';
}
$array1 = array('Volkswagen' , 'Renault' , 'Land Rover');
echo' <select name="cars" onchange="this.form.submit()">';
foreach($array1 as $cars){ ?>
<option value="<?php echo $cars; ?>" <?php if($mycar==$cars) echo "selected='selected'"; ?> ><?php echo $cars; ?></option>
<?php
}
echo'</select>
</div></form>';
echo 'your favourite car is : '; echo $mycar;
?>