Fazer 8 mpg and range

[Didier9]

didn't explain his riding style though.

That is one big factor, but the type of traffic and how long a single stretch is also factor in.
It's much easier to do 180 miles one time than 18 miles 10 times with a given amount of gas. Each time you start the engine cold, it's not going to be at full efficiency for several minutes until the coolant and the oil are at temperature. If you have a carburated engine and run the choke, it will be worse. If you warm up the engine before you get going, it will be even worse, regardless of carb or FI.
Also, if you live and work half a mile from the highway, it will make it much easier than if you have city traffic the whole way.
I have not done careful calculations with the bike, but with my car, even though I only have highway to work (except for the 3/4 mile from my house and a couple of traffic lights), I average 22 mpg on my 12 miles trip going between 45 and 65 with one or two occasional traffic light stops. If I take the car on a long trip, I get 25 or 26 mpg doing 70-80 (and only stopping for gas).