It's unlikely that someone will specifically want a ford focus, espcially as there is value to be had in better makes.
I would emphasise the AUTO and engine SIZE (I assume it's a small to medium car) in you add's. Word it this way on buyandsell, donedeal and gumtree. In my view a local paper ad, is the only one worth paying for in especially if your regional, as some people dont want to travel far when buying a used car.