From what I can tell, it does make a positive difference to the car.
I have found that it is a little quieter, throttle response is up, and boost seems to ramp that little bit quicker.
It does also make the car slightly more economical (2-3mpg), even when giving it booty everywhere!
I don't pay for any of my fuel, so I would have it anyway on the basis that it
should be the best stuff available.
Give it a whirl. You need to run a few tankfulls through to reap all the benefits, so I don't think its really worth it if you just top up your tank with it, or don't plan on using it all the time.
