Many of the more interesting hybrid vehicle designs are coming not from the established automotive giants (whose stature seems to be shrinking daily), but from innovative smaller firms. Lightning Motors has come up with a design that combines an efficient diesel engine with a 150-horsepower Rexroth hydraulic hybrid system to produce a sleek machine, which will be unveiled at the Denver Auto Show, capable of achieving 100 miles per gallon. The associated article in Wired.com, 100-MPG Hybrid Evokes the Classic '63 Corvette, by Ben Mack explains how a technology originally targeted for delivery trucks adapts quite well for automobiles.
Hydraulic hybrids use a diesel engine to drive a hydraulic pump, which charges an accumulator - essentially a high-pressure tank. The accumulator, in turn, drives smaller pump motors that send power to the axle or power the wheels directly. Such systems have been around since the 1980s but limited to delivery trucks - UPS plans to roll out the first of seven sometime this year - because the accumulators are bulky and tough to fit within the confines of a passenger car. Lightning Hybrids isn't saying how it will address this problem but insists it is "working night and day" on it.
The Lightning Hybrids look like strong contenders for the Automotive X-Prize competition. First-place winners will walk away with ten million dollars.