The potential for hydraulic hybrids is great — and widely varied. Heavy off-road equipment and delivery fleets are logical applications. In time, hydraulic hybrids will make sense in personal vehicles. Meantime, I continue to be intrigued by the possibilities in racing. Jeremy Kaminski of Kamien Performance Cars in New Buffalo, MI, writes, “Some supercars can put out about 600 lb/ft of torque to the wheels. Is this possible...

The biggest gains in fuel economy and emissions reductions will come when we remove the mechanical link between the engine and wheels. De-coupling the engine load from the road load allows the engine to run continually at or near maximum efficiency. A hydraulic hybrid does that, and offers more potential for greater fuel efficiency gains and emission reductions right now – more than electric hybrids, full electrics, and alternative fuels....