2008 Fatboy with 58K miles. I average 36-38 with most of my riding 75-80 on the Kalifornia freeways. I'm a big guy so for me it's like riding 2 up all the time. On a recent trip through the Rockies I got 50 mgp for the first time ever.
Also I'm runing a Daytona Twin Tec fuel management that I run on the rich side. I'd rather run cooler than get better mpg.

 

'07 RKC and I get high-40's on highway trips...better'n my 6-spd Dyna!

 

Constantly in the upper 40's (46-48)....and
occasionally lower 50's (51-52).
All dependent on wrist position, and solo or 2-up.

 

2006 Street King Classic) see pic. Big air Kit, Stage 1 D/L and SE pipes.

I average about 42 MPG, and have been as low as 38 and as high as 50. Depends on my riding. Open that throtle on the highway and Bamm I drop. Best I got was 209 miles before I rolled in for Gas. took 5.1 Gals in a 5.0 tank. Go Figure

 

2005 Road Glide, stage one A/C, slip ons and flash.... stock otherwise
39-42 while commuting, (lots of heavy throttle, and on and off the gas
48-52 while out cruising the back roads, just enjoying the day

 

32 to 36,2010 Tri-Glide.

 

Mid 40's with a high of 50 while riding at high altitude.
Note that several of the posts with mileage in the 50's got it while riding at high elevations.

 

My last check was 48 mpg

 

WOW! I REALLY must need to get mine tuned! With SE A/C, Rinehart True Duals, 255 cams and PC-V w/ Auto Tune purchased & mapped by Fuel Moto... 31-35 MPG! Now, I'm about 290# and ride solo until the weekend then the OL climbs on & add's about another 120#. I also like the sound of the Rineharts & the TQ of the 255's, so this keeps my right wrist moving around quite a bit... but still...31-35!!

 

I have only had my bike for a few weeks and this past tank I kept track.

2005 Road King Custom
95ci kit
41 MPG
about 50/50 Hwy/City

Now yesterday when I was leaving my house my neighbor came over and was chatting with me. I knew I was low on fuel but while I was sitting on my driveway (slight down hill) the bike cut out (no low fuel light on). So I started it back up and rolled down the hill, and I thought that I would be OK while on flat ground. Got to the end of my street and it cut out again. I was able to get it the 1 mile to the gas station but it tried to cut out on me one more time going down the road. Bike took 4.8 gallons so I was surprised that the light never came on. The last tank of gas it came on just about the time that the needle hit the red zone of the guage. Oh well, I guess now I know not to trust it. Which I already really did not I just wanted to push the tank a little to see many miles I can get out of my normal daily commute.

Phil