Hybrid-car experiments go back 100 years, but most were prototypes or stillborn marketing efforts. What's exciting now is that two models, the Toyota Prius and the Honda Insight, will be entering the U.S. market in the next few months, backed by the full might of these very savvy auto giants. There are two types of hybrid electric cars, series and parallel. In a series hybrid, a small gas or diesel engine generates power to drive an electric motor and recharge the small battery pack that these cars usually carry. The fossil-fuel engine, in effect, serves as a mobile charging station.
Parallel hybrids have two discrete power systems, gas and electric.
Either one can propel the car, but when they work together they provide the kind of power needed for quick acceleration. The system in Toyota's breakthrough Prius, which has been a hit in Japan since it was introduced there in 1997, incorporates elements of both the parallel and the series hybrid. The engine shuts down automatically when the car is stopped, which means it won't pollute when stuck in traffic jams. All this helps the Japanese-market Prius reach 66 miles per gallon and 870 miles on a tank of gas. The Prius will not arrive in the United States until the summer of 2000.