Having lived and driven in Europe, there are marked differences in the fuel in every country, in Italy the fuel stinks and that smell permates all cities, Milano, Rome even in the canals of Venis you have the smell of the fuel, and even in Europe Shell fuel is not that good, Esso and anything other than Shell is what we used.
There are sertain international standards, and as mentioned aditives change from brand to brand, I noticed the amount of kilometers or miles that the various fuels rendered for the trips taken.
Next year the price of fuel in Mexico will go up, unless something drastic happens.
navegator