If you've got access to a database, then it would be easier to have a table with a primary key of the short name and the URL. You can then use the following code:

header('Location: '.query("SELECT url FROM table WHERE name=$model"));

With query() being whatever function is necessary to get a result from your database and return a single value.

To do a switch, use the following:

switch ($model) {

    case 'ford':

        header('Location: http://www.ford.com');

        break;

    case 'empeg':

        header('Location: http://www.empeg.com');

        break;

}