I was using premium fuels in my Focus but when the price of diesel started to drop the price of premium diesels seem to stay high.
I've filled up with Murco diesel and the car sounded a lot more coarse than it did on BP Ultimate.
I started adding Millers Ecomax in generous doses to Tesco diesel and it runs as well as it did on BP Ultimate.

I used to put two stroke oil in the fuel of my previous diesels but unsure if it is DPF safe which makes me a bit nervous about putting it in my Focus.