- implode: documentation ( source)
<?php
$cars=array("Dodge"=>array("Avenger","Challenger","Charger","Dart"),"Toyota"=>array("Highlander","Tundra","Corolla"),"Nissan"=>array("Sentra","Altima","Maxima"));
echo "Make: Toyota"; echo "<br><br>";
echo implode(',', $cars['Toyota']);
?>