Scientific?  No, but at least we get a general idea of the efficiency differences between the Tesla Model S P85D and Model S P85 in this efficiency comparison video:

"Leg 1 of my efficiency test of my new P85D (firmware v6.0 2.0.81) and a P85 on the same route, at the same time, at roughly the same speeds."

Though far from precise, it's still rather easy to see which Model S consumers more energy per mile.