Because my car isn't highly tuned (or even tuned at all for that matter): I tend to use regular unleaded from whichever station is closest when my fuel light comes on.
I filled up with Shell V-Power 5 or 6 times in a row back when I was feeling a bit plush and I can't say I noticed any difference at all... Then again, my engine's compression ratio is likely to be so low that I wouldn't get knock with 80RON
