Parker is currently working with advanced energy recovery systems in vehicles, but don't expect to see such a thing in your family vehicle just yet. Today's car engines are constantly ramping up and down as they switch gears, running over a wide range of perhaps 500 to 5000 rpm. Kovach claims that running the engine at the "sweet spot" with constantly variable transmissions (CVTs) can improve efficiency and reduce emissions.

"Honda's got some vehicles on the road now with mechanical bands," says Kovach. "The only problem is that those mechanical bands can't take a lot of power. They're good for light vehicles, but America moves by truck.

"Right now, we have systems running in over-the-highway trucks where we have replaced the mechanical transmissions with hydrostatic transmissions, and we're increasing efficiency and reducing emissions. They can actually provide better overall system performance than many of today's automatic transmissions."

The efficiency of a hydrostatic drive is calculated by multiplying the efficiency of the pump by the efficiency of the motor. Kovach explains, "when typical hydraulic motors ran at 70-80% efficiency, total system efficiencies were just over 50%. Today, some components are running at 95-98%, giving more workable total system efficiencies of perhaps 90-95%.

"States such as Connecticut have now enforced anti-idling laws for a lot of their buses ... at school bus stops, it's been proven that children in some areas are getting asthma from diesel particulates," says Kovach, stressing what manufacturers and system designers are up against, and how critical the environmental issue is.

Kovach says that in current tests, he sees 50% increases in efficiency and 40% reductions in emissions using hydrostatic drive systems in heavier vehicles, such as trucks, buses, and delivery vehicles.

Another way to increase vehicle efficiency is to capture some of the energy normally wasted in the braking process. In the last few years, Eaton has championed a hydropneumatic system called Hydraulic Launch Assist. Brad Bohlmann, Eaton Hydraulics' business development manager for advanced technology, says, "The HLA system lowers fuel consumption and CO2 emissions by 25-35% and other regulated exhaust gases by up to 90% in vehicle applications that make frequest starts and stops in their normal daily routine." The HLA system uses an accumulator to store the energy normally wasted during braking. That energy is released as needed for acceleration, saving fuel cost, extending brake life and reducing wear on the engine and braking system.