Reuters had a pretty good article on hypermiling and hypermiling techniques a few weeks ago.  The article also mentions the nearly omnipresent (at least in hypermiling articles) Wayne Gerdes.  The authors claim that drafting is a popular method used by hypermilers but I think this would be widely disputed.

Known as 'hypermiling,' the method can double gas mileage, even in gas-guzzling vehicles that would normally get less than 20 mpg.

Promoted on a growing number of Web sites, hypermiling includes pumping up tires to the maximum rating on their sidewalls, which may be higher than levels recommended in car manuals; using engine oil of a low viscosity, and the controversial practice of drafting behind other vehicles on the highway to reduce aerodynamic drag -- a practice begun a few years ago by truck drivers.

and,

Deron Lovaas, vehicles campaign director at environmental group the Natural Resources Defense Council, said most hypermiling techniques are "sensible recommendations" that could drive down demand and even prices if widely adopted.

"We should be looking under every rock for potential energy savings," he said.

He said he could not recommend drafting behind fast-moving trucks because it could potentially lead to highway accidents.

Hypermiling can even make fuel-sipping gas-electric hybrid cars more efficient. Chuck Thomas, 50, a computer programmer from Lewisville, Texas, said he has been getting 71 mpg from his Honda Insight, a hybrid whose EPA rating is 58 mpg, in the two years since he has been hypermiling.

Among Thomas' techniques is "pulse and glide" in which he accelerates and then coasts with the engine off until around 15 mph when he kicks the engine back on and accelerates again. "It's the automotive equivalent of skateboarding," he said.

The rest of the article can be found here.