The Hayes bike, based on the new military model,
is supposed to be available in March.
http://www.dieselmotorcycles.com/
102mpg 600 mile range at 55mph.
There have been a few diesel bikes:
http://journeytoforever.org/biodiesel_bikes.html
What I find more fascinating, is the Hydrogen bike.
100 miles on a tankful.
They talk about also offering a Hydrogen generator the size of a shoebox
that can make a tankful for 25 cents.
http://www.envbike.com/
It all sounds unlikely to me though. At least in this decade.