I have the Centurion plans... got 'em back in the day, when they were brand new. I had a Spitfire then too, but for whatever reasons "my" Centurion didn't get built (IIRC I couldn't locate a reasonably priced diesel engine at that time- pre-internet shopping was sooo much harder!).
Another thing that really seems disingenuous today is the mileage claim at 35 mph... yes, it's ridiculous, but back then most fe claims were ridiculous. We had been gradually moving away from nonsense and towards usable fe estimates until, IMHO, they were quite good with the last generation of EPA tests, which have now gone downhill to reflect the stupidity of the average driver today.
