I try and run Vpower 99 or momentum 99, if that's not near where I am then the next best thing is super unleaded 97 which BP, Esseo, sainsbury's, etc sell. Only if I'm desperate I go on 95.
Mainly use Shell and Tesco for the discount schemes, just got £5.50 off at shell and now I'm a v power member and have the magazine.
I normally get between 300 and 350 a tank.. I've got near 400miles before but went through loads of average speed cameras and stayed at 60mph in between but normally get bored and fuel economy goes out the window.