Problem with order_by

[eluser]bondjp[/eluser]
I'm having a bit of a problem using order_by.
I'm trying to oder one field but i want that the first value to be assigned by me like this:

carbrand
Lamborghini -> Assigned by me
Alfa Romeo
Aston Martin
Audi
BMW
....

Using this:

Code:

$this->db->order_by('carbrand', 'asc');

How can i use the order_by to achieve this?
Thanks.