Done about 4500 miles on the beasty at 90 mpg and would have been doing about 35mpgish on the Bandit and about the same cost for running the LPG powered BMW sidecar!
Miles..MPG.Gallons....Litres.....Cost @ £1.2 l
4500...90.....50...........227.5.....273
4500...35.....128.57.....585.......702
So £702 -£273 = £429 saved! and I reckon I built the bike for between £350 and £400
So by Christmas I would have also saved the cost of the new engine bits and machining making the bike essentially free