Eaton, which is better known for its involvement in supercharging muscle cars, has a thing for saving fuel, too. According to a writeup on the outfit's website, it's working up a series hybrid hydraulic system
to replace the conventional driveline. The SHH system will wed a high-efficiency diesel engine and a custom hydraulic propulsion system, and by operating at its "sweet spot," it stands to reason that lots of gasoline will be saved as it runs. Better still, the setup involves regenerative breaking in order to recover and reuse energy that's typically wasted, and the engine can safely be shut off when not needed in order to save additional fuel when waiting at a stoplight. So, where is this stuff headed first? UPS trucks, naturally.