Do fuel brands/grades really matter?

[Neosophist]

Wow that was seriously informative...

I have one more question.

What effect does the euro II, euro III or euro IV ratings for fuels have when used on our engines?

I read up that the ratings show the amount of sulphur in the fuels...

Will the lower grade just mean that the exhaust emissions are not so environment friendly, or will it build up carbon in our engines?

That was mainly diesel. which is why it now costs more than petrol.

Older diesel had lots of sulpher and was smelly and smokey, diesel is normally a dirty product.

To reduce emissions inline with euro laws the diesel is refined a lot to take out the sulfur. I seem to remember sulphur being a good lubricator so they need to put more additives in the fuel as well as refining it, hence the high cost.

Just like when they scrapped leaded petrol.