$(document).ready(function(){ 
	$('select[name=dealer_id]').change(function(){ 
		var dealer_id = $('select[name=dealer_id] option:selected').val();
		
		$.getJSON("/ajax/forms/test-drive.php?dealer=" + dealer_id, function(data){
			
			$('select[name=test_drive_car_id] option').remove();
			
			$.each(data, function(i,item){
      			$('select[name=test_drive_car_id]').append('<option value="' + item.id + '">' + item.name + '</option>');
    		});
				
		});
		
	});
});