[Dave Samson]

Richard,
A little off the point, but I just drove 2,400 km to our Nationals and back from the Gold Coast running a supercharged Commodore engine, albeit all on vacuum on the highway, 0.68 5th on a Tremec TKO, 3.45 diff. and averaged 21 m.p.g. fully laden with 2 people. Around town I get 14 mpg. That ratio of 50% better fuel consumption on the highway is pretty consistant for my other 3 vehicles.