fuel discussions like this are pointless.
Its all dependant on what area you are in, and what servo you get your fuel from.
I've run ultimate from my local servo and only gotten 400km from a tank, highway driving, but from another one, 550, exact same driving.
Also vice versa with v power.
What you really need to do is determine what servos are in your area of filling up.
Then get a tank of of each and see with what one your car runs the best, and stick with that.
Bookmarks