Brilliant. So sexy it brings a tear to my eye. And I've learned a thing or two about steam systems.

2 loops- one flashed from exhaust gas, the other from engine coolant AND from condensing the primary loop. Both superheated- extending turbine blade life.

The temps (<450F) and pressures are certainly low enough to be able to use stainless, which lets you get away with mostly ignoring boilerwater chemistry issues. This needs to be a seal-it-and-forget-it system; perhaps its not even water that's used as the working fluid? Refrigerant of some sort, perhaps- the better to flash at lower temps near atmospheric pressure and avoid corrosion issues.

"Elegant" comes to mind as a description. Of course "elegant" is code for 'rather complex and pretty cool when it works, but a bear to keep running reliably.'