I think most of these figures are taken out of context.
When statisticans use a car to get the combined fuel economy, they usually drive it in the middle of the day, and on roads where they will be moving, and only go into the town occasionally. This way, they will get better overall economy.
I sit in traffic every morning and come home at over 100 every evening. I have been averaging 25.6 mpg and 38mph. I'm sure if I had a clear run each way and I cruised at 70 I would have an average of about 40mpg. But Alfas are for driving, not for plodding along at 70.
I've found that Optimax is better when pushing the car, but much worse in traffic, so I stick with 95 Unleaded.