Originally Posted by dan50
For what it's worth, I have noticed no real driveability/economy difference between premium and regular.
I have, a few times I've gone back to filling up with regular and I start to get that hesitation on acceleration (that a lot of people blame the trans for) and it doesn't run as well at lower RPM. Some low RPM torque is definitely lost in my car when running on regular gas and it just doesn't run as smooth or as powerfully overall. Mid-grade is better than regular but premium makes it run so well that I always put it in now. I don't drive my car a great deal though, I have a separate company vehicle and therefore I've averaged less than 600 miles per month on the Focus since new so it's not a huge cumulative expense for me to run premium gasoline in it all the time.