Are you sure that's not miles per litre?

Yes that must be mpl red dog...

So about 73 mpg which is pretty good.

Yes Sorry, my mistake. Miles per litre, so 16.1-16.4 = 73-74.4 mpg. Not so bad.. about 15 or 16 mpg over the CBF600.
A little way to go to match Datas' 90.5 though.. Note to self: Must try harder.

I never believe any fuel consumption figure a computer shows - the only real figure is the old fashioned sort where you fill up your vehicle and divide miles travelled by fuel put in! My car's computer insists that its giving me 42mpg, but I only get around 35 at the pumps.

My 2015 mpg has improved as it’s got older. I regularly get high 60’s low 70’s now whereas earlier it struggled at 10 mpg less than that. I notice it’s much lower once you start to exceed 70mph. However, ridden sensibly and smoothly they’re very economical for a 400.

Since mph is arrived at by dividing distance/time, if the mph is out it could be either faulty distance measurement or ( much less likely) the time intervals. I would guess that the "econometer" will use the same distance input therefore surely the mpl/mpg figure can't be any more accurate. As you say Mr G, a pen and paper might be better, but you would still have to have a better measurement of distance or you will still be 10% out.
Stibbs, after a lifetime of riding bikes I know that most Japanese 600 fours , ridden gently at 55-60 mph usually return around 72 mpg. (and I've had a number of them) but I think a single or twin, in a gentle state of tune will be the best for economy. My old BSA 650 used to return around 80 mpg on my rides to work in the sixties, and i've concluded that 55-60 is the most economical speed for any petrol powered vehicle. Of course it's just my opinion, and my reasoning could be out by a good 10% due to the amount of white wine in my bloodstream (about 10%)

Yes, errors in the speedo will affect either way of calculating mpg - but the figures should be the same from the computer and pen&paper, but I've found they normally aren't!
Another big error in a one -off mpg figure is the filling of the tank....on the Tmax anyway, getting it filled to the top is very difficult and you can often under fill by a few tenths of a litre as its hard to know when it really is full.

Yes I've been using the "Data Burp" on my fill ups with the Burgman. After filling to the top (sidestand or centrestand) giving it a to and fro shake produces a big "burp". I don't know if it means it always reads the same, but it's amusing anyway!

I know it's a few weeks since the original post, but my excuse is that I have only recently joined the forum!
For not identical, but similar reasons, I have come back to autos. The Burgman 400 is the one I went for.
I did look at the 650, but couldn't even heave it about on the level shop floor. Plus the 400 has such a wide following.
If you want to do your own maintence MicBurgsma on YuTub gives all the knowledge you will ever need.
Not had chance yet to use it much, but one 50 mile run (locally!) showed it goes well enough, and the onboard
computer reckons that its doing 67mpg.