Only by a very slight amount as its more resistant to knock so could run it leaner/hotter.

Same amount of fuel, same air/fuel ratio, simple as that.

Simple fact is that car would not be running Cossie greens and there would be no reason in any way for it to run them.

Chip says a lot of things and backs up lots of things, dont mean hes right just because he will argue black is white for 10 pages