Hybrid drivetrain systems combine, typically, combustion engines and electric motors. (There are the prototype or not-ready-for-mass production fuel cell hybrids, but . . .) As there are more of these systems being developed, there is a need for commercial test solutions. So SAKOR Technologies (www.sakor.com), which develops test systems for combustion engines and for electric motors, has combined several of its products—namely, the DynoLAB PT Engine Test Cell Supervisory System with elements of its DynoLAB EM Electric Motor Test System, and AccuDyne AC Motoring Dynamometers—and developed the HybriDyne, which is said to be capable of calibrating the performance, efficiency, and durability of hybrid drivetrain systems.