// get all group id information
$groups = Auth::get_groups();

// print driver and id info for each group user is in
if ($groups)
{
    foreach ($groups as $group) // Each $group is a Auth\Model\Auth_Group Object.
    {
        echo 'Driver: ',$group[0],' with group ID ',$group[1]->id,'<br />';
    }
}
else
{
    echo 'Nobody is logged in!';
}