I have always used either Shell V Power ( Optimax as it was once known) or Tesco Momentum in my previous cars and now in the GTI P/P. Did put some 'new' V Power Nitro in the other day and to be honest, didn't feel any different to Momentum, and it was 6p a ltr dearer.But the people in the know say you have to fill the tank a couple of times for the ECU to adjust. Whether this is true I am yet to be convinced.