Originally Posted by RonMaiden
If you have to run premium in this Focus engine to make it run right then you probably have a problem somewhere else since higher octane shouldn't be a band-aid.
It is a high compression engine 12:1, and high compression engines need higher octane fuel. I believe in Europe cars are required to be able to run on 87 due to high fuel prices. So Ford works the ECU and cam timing to make it run on 87. Doesn't mean it will run well. In reality, this is a premium only car, capable of running on 87. Most on here experience an increase in MPG that offsets the added cost of running premium, and in most cases cost less per mile.