No price was given but we feel it's safe to assume they weren't cheap. UPS did state that if they were manufactured in high volume, the extra expense could be recouped in a three-year period from fuel and maintenance savings. This HHV is said to save fuel by using the hydraulic equivalent of regenerative braking, operating the engine more efficiently and stopping the engine altogether when it is slowing or stopped. When it is running, the high-efficiency diesel powers a pump instead of a transmission and incorporates storage tanks that hold pressurized hydraulic fluid. To see a nice visual representation of what's involved, hit the jump for the official schematic as well as a short bonus clip of a hydraulic hybrid in UPS colors under way.