Chrysler is fitting an EPA-patented hydraulic drive system into its Town &' Country minivan.

Today, Chrysler and the Environmental Protection Agency (EPA) announced they would cooperate on adapting a hydraulic hybrid drive system for a Town & Country minivan. The EPA owns the patent on hydraulic hybrid systems, and currently is testing the concept in large commercial vehicles, such as UPS vans. Ford and the EPA developed a hydraulic hybrid diesel SUV in 2004 that was cited as getting 85 percent better fuel economy.

In current use, the hydraulic hybrid system stores kinetic energy in hydraulic fluid tanks, releasing the pressure to drive a vehicle's wheels. Similar to an electric hybrid, if there is enough pressure in the system, the engine can shut off when the vehicle is stopped. Hydraulic pressure provides a boost for acceleration and can get the vehicle moving from a stop. The EPA says overall fuel economy increases 30 percent with the system, while city economy increases 60 percent.

For the Town & Country, Chrysler envisions a series hybrid application, where hydraulic pressure is the only force turning the wheels. That pressure is created through regenerative braking and from a 2.4-liter four-cylinder gasoline engine. The hydraulic fluid tank, referred to as an accumulator, holds 14.4 gallons at 5,000 PSI.

The main challenge for Chrysler and the EPA in this new project is to make the system more compact, taking it down from its commercial size deployments to a size that can be fitted into a passenger vehicle.

Don't expect to see a hydraulic hybrid Town & Country on the market anytime soon. Chrysler is exploring multiple fuel-saving technologies, some of which come from new owner Fiat.