Depends on who you ask, right? My dad ran premium in his old escort and it ran better towards the end of its life. I run 89 in my focus and I feel there's some, though small, gains
Avant Garde M310 18x8.5 Satin Silver. Engine Cover w/ Sonic Blue Accents. Sonic Blue Door Grabs. KW V1 Coilovers. OEM Titanium Headlights. OEM Replica Spoiler. K&N Air Filter.