Regarding the additives.
I haven't heard anywhere (other than from people on here) that the Tescos fuel DOESN'T have additives. I know they haven't mentioned it in any of their advertising, but does that mean it doesn't have any? I don't know - maybe it does.
All I know is that since about April this year we have tried to use more Tesco fuel and less Optimax (which we always used in the past) after reading about some members here having problems with valve stem oil seals and the blue smoke issues while running OPtimax. They reckoned they had noticed the problem become much less pronounced when they switched away from Optimax. Since making the switch to Tescos fuel ourselves, we rarely see any blue smoke anymore - it was a daily event before!
Also, there have been numerous occasions where after filling up with Tescos 99, the car has gone like a rocket! A very noticeable difference that made me think the wastegate actuator hose must have popped off! (it happened on my car this year and caused the car to over boost. Great for the acceleration but NOT for the engine!)
I know where I'll be buying my fuel from now on, but hey! I'm only a woman so don't take any notice of me!!