Ok Ive been doin alot of old school data logging with mpg, plug gapping, octane, and tire psi.
One thing I have definitely noticed is how there is NO gain what so ever with higher octane in a stock 1.4ltr whether or not you have an auto or man trans. Trust me on this, I live in TX speed limit is 75mph and there is tons of flat roads around to do equivalent testing. Our cars are stock tuned for 87 octane. Tire psi seems to do best at 33psi, I cant belive some of yall would go up to 40+psi I just guess yall like uneven tread wear. Spark plug gapping... I can talk about this all day, but Im not, Ill be breif. Our stock gapping is .026-.028, there is a -/+ tolerrance our ECM allows. If you have no tune, dont mess with the gap, leave it at .028 max. I have logged and recorded gaps ranging from .024 as a base all the way to .038 as the highest. With two differnt brands, Denso and NGK. If you want a good plug that wont be fouled or having to gap check every 10k-25k miles, go with the Denso, it has a stronger plug. Ngk is a great plug, but they have sadly dropped in quality that used to be the plugs to run. But anyways, if you dont have a tune psi at 33, leave your plugs gapped at .026-.028, and dont waste your money on higher octane fuel, that is just going to end up costing you in the long run. I might be retired, but Im still Goodwrench certified. Now once you have a tune, rock out with with .033 gap, 90+octane, and get some power goodies, then youll be good. Remember, our cars have an under power engine in a heavy car plus us and what ever else is in the car with you. GUYS please dont air your tires up to 40+psi thats a recipe for disaster. Oh crap forgot to add best MPG I got was 31 avg mpg. 33psi, .028 gap, 87oct, ac on full blast me my wife and three kids with a weeks load of luggage. 418mi trip one way. Avg speed was 70mph.