Yes, when I use high octane unleaded, it definately improves running, and if I stick to under 50, on road, I probably get better MPG, but even on LPG, I'm still getting small return! does the carb condition make much of a difference using Gas? I suppose the phrase cake, and eat it comes to mind! It is indeed a pleasure to own such an amazing piece of engineering, that has survived 42 years of driving! (which,unfortunately has ears, and a 5th sense when it comes to knowing when there is some mission I need it for, and throwing a sicky)..