Try this website.
http://totalmotorcycle.com/MotorcycleFuelEconomyGuide/Honda.htm

While you see Honda in the address you can access most major motorcycle types.

The mileages posted are from the riders themselves not the manufacturers.

Currently, I am getting 60mpg on my '08 Honda 750 Shadow Spirit.  Hope this helps.  

Someone mentioned that they can't wait to see the majority of traffic become two-wheeled.  I'd like to see that myself.  I'd also like to see more scooters out there, that's why I wave to every one of them.

I met two people yesterday in Modesto, CA.  One had recently bought a bike and took it out for his third ride.  He was gradually getting a little faster each ride.  I met another woman who bought a bike but would only ride it during the day on the weekends.  I have a feeling that we are going to see a ton of motorcycles and scooters on the road in the fall when everyone starts getting more comfortable.  

I've heard from local motorcycle dealers that they can't keep scooters in stock and that the 250 sport bikes are also selling like mad.  I haven't really noticed much of a difference on the road yet.  The real test will be this winter.  Hopefully there will be more than just me and one other guy.