Just to throw in my experience. I bought my 2012 Tiger at Christmas of 2012, and I have put about 4,500 miles on it so far. It took about 2000 miles for things to break in and fuel mileage to really iron itself out.
I use my bike largely as a true 50/50 dual sport, so I spend about half my time slabbing it to where I want to ride, and then about half my time on anything from ATV trails up to forest service roads. In this sort of riding I get around 43-45 MPG. If I am riding a lot of big open dirt, or back roads where I am riding at 45-60 in 5th/6th gear, I run right around 50 MPG. If I am fully loaded with panniers on blasting down the interstate at 80-85, mileage plummets to around 35-40 MPG, if I back off to the 70-75 MPH range consumption seems to increase linearly to around 40-43 MPG. My average for the life of the bike is just over 44 MPG
Everything is still stock, no sprocket changes, nothing more than the stock fuel map, no aftermarket exhaust. I weigh around 220, and don't often have a passenger. That being said, I haven't noticed any significant changes in consumption whether the bike is loaded or unloaded.
50/50 Dirt/Highway = 43-45 MPG
45-60 MPH in 5th/6th gear = 50+ MPG
80-85 MPH full loaded = 35-40 MPG
70-75 MPH fully loaded = 40-43 MPG
Also, I have found the on board fuel consumption estimation to be quite accurate, with it tending to underestimate consumption by 1-2 MPG. Also, the low fuel light comes on with 1.3 gallons remaining on my bike. So my rule of thumb is, if I hit 185 mi when the low fuel light comes on, I am averaging 50 MPG, if I am around 150 than I am running around 40 MPG.
I'm not retarded, I just don't proofread my posts.