Can't give you "credit" for approximations, not that I'm really keeping the list updated any more, anyway.

Yeah, more pressure will help. It'll help more than you think. It's pretty surprising. Try something like 42-48 psi. Hardcore hypermilers will tell you to run 60! More pressure keeps the tire rounder and you lose less energy to heat in the flexing of the tire, less rolling resistance and all that.