Which Fuel and WHY?

Hi Member's

I am sure this had been covered before but could not find anything.

We all Love our car's and all worry about what we put into them so it brings me to this topic.

It could be all in my head but i honestly feel my car responds and behaves differently with different fuel.

I find the following,
BP - Best Millage and Smooth Power

Sasol - Best Power (Engine gets a little ruff with regards to sound and also a small burp from the exhaust every now and again) and Millage comes down a little compared to BP.

Engine - A combination of BP and Sasol, Good Millage and very Constant Power (More than what I get from BP and a little less than Sasol) but the overall drive is much smoother.

Shell - I find the Most Power is archived with Shell but find that the car burns Black and Millage is very bad (+-50KM less per tank)

I have not ever used any other Fuel on my BMW but i have used the Following on my VW,

Caltex - More Power than Engine and BP with better Millage (Car seems to idle a bit more heavy)

Please share your take on the above and experiences.