Hey bubs,
there are lots of brands and formulars of fuel on the market, like shell, esso, 76......do u care about the brands and formulars that u pump in your car. my friend kept on telling me that x brand's y formular surpasses the performance of all others(eg. faster from 0-100km or run longer per galon).

1 have u intentionally set your car up to test brands+formulars?
2 did u notice the diff on switching brands/formualr?
3 what brands and which formular do u think is the best for :
i)daily use, ii)best buy, iii)performance?
4 is it only psychological only?

my wife worked with a chemical company long time ago, she told me that the addictives make big diff. what do u think?

As part of my job, yes additives CAN make a difference but nothing like wow or best 0-60 runs and such. I run gas quality and EPA environmental tests. Yes the big names out there usually come out quite high in cleanliness and quality, Esso, BP, Shell etc. Now the one thing we have noticed to influence a lot of tests is LOCATION. You could have samples of lets say 3 different Shell stations and all three would have enough variations on them to seem as if they came from totally different sources sometimes. Soil composition, distance to natural running water <surface or underground> soil temp, etc. these factors among others, have a significant <on chemical tests that is> impact on gas quality per location. Except for what we call 3rd parties gas stations <can't mention names but i.e. "Los Taquitos Gas Station", u get the idea..> which usually have the highest levels of impurities, just stick to a big name company. From there, if you notice a specific station not having good quality gas, just try changing locations first and see if it continues, don't always blame the gas source itself. Hope this helps :D