I hear ya. I'll try it out. I only take my 135i out on the weekend, or in nice weather for fun. I have another car for my dd so I never get good gas mileage with the 135 anyway
But when I have to travel far to an autocross event I usually just get on the interstate and get into 6th ASAP and just relax... Seems to work fine... I could be wrong but, i think if I did follow what the manual says that I would get a tad better gas mileage, but I haven't cared enough to test it out lol.