i just did a 400KM highway run and instead of using 87 octane, I used 89 octane and got 6L/100KM. That is by far the best mileage I have ever seen. IN the past past with 87 octane, i have gotten 8~9L/100KM doing 115KMPH. So I guess I'm going to run a few tanks with 89 octane and do my regular driving and update you folks in a few weeks.