Another variable when flying to Vmd (max range) is that you are at the very cusp of being behind the drag curve, throw in a little turbulence, a temp or wind change and you find the A/T has to constantly adjust power settings to maintain the speed at Vmd. Power changes burn more fuel than a slightly higher power setting that doesn't require as much adjustment.
A max range CI is fine in theory, but very rarely ends up doing anything other than burning more fuel than it theoretically should.