Mines was sluggish once using 95 ron. Had no option i was in middle of nowhere and petrol light came on. Checked shel petrol station app on phone and wasnt one close enough to me. So i came across a weee petrol station that only had 95 ron.. put about £15 in just enough to get me to nearest shell station and tried to drive off boost there. But the odd moment i did hit boost the car was sluggish /lumpy when the turbo did kick in.. so i put it down to the petrol. Always used vpower or on odd occasion momentum99.
Tho i do know i get more mpg with tesco momentum than i do out of vpower. But were talkin an extra 20-30 miles out a tank roughly id say