UPS' Hydraulic Hybrids  

Gas 2.0 has a post on a UPS test of hybrid hydraulic delivery trucks - UPS is First in Delivery Industry to Test Hydraulic Hybrid Vehicles: 50% Better Fuel Economy and 40% Lower Emissions

In partnership with the US Environmental Protection Agency, UPS will begin testing a small fleet of hydraulic hybrid delivery trucks in the United States. The new vehicles can achieve 50-70% better fuel economy, a 40% reduction in greenhouse gas emissions, and pay for their extra expense in less than 3 years. ...

The hydraulic hybrid drivetrain eliminates the need for a conventional transmission and increases fuel economy in three ways:

1. A large amount of the energy that is otherwise wasted in braking can be recovered to pressurize the hydraulic fluid.
2. The engine operates much more efficiently — similar to a hybrid electric car, only without the bulky batteries
3. The engine can easily be shut off and instantaneously restarted during regular driving — such as when the vehicle is slowing down or stopped at a light.

UPS has been developing what it calls its “green fleet” over the last several years and currently has more than 1,600 low carbon emissions vehicles including electric, hybrid-electric, compressed natural gas, liquefied natural gas, and propane trucks.