[Jeffand]

Right now thier are two basic types of hybrids. Series hybrid and parallel hybrid.

:idea:
In a series type hybrid when ever the vehicle is in motion the gas engine is spinning. When the vehicle stops moving the gas engine stops. The purpose of the electric hybrid drive is to provide additional torque for acceleration. It can also provides regenitive braking with the engine spinning but with no fuel or spark. The Honda insight, and Civic are series hybrids.

In a parallel hybrid eather the electric hybrid drive or gas engine can be running. Or both may be in use at the same time. So at low speeds you may be running only on the electric motor. The engine only starts when additional power is required, or the hybrid tracktion battery needs charging. So the on board computer selects the most efficient method of propulsion. The Prius and the Highlander are parallel hybrids.

A parallel hybrid will produce better gas mileage than a similar size series hybrid vehicle. This is one of the reasons why the Prius gets better gas mileage than the Civic.

This is not a nock on the hybrid Civic. Because it's a cool car also.

 

[john1701a]

Here's some detail you may find informative...


Not Really a Hybrid

Type I (Low-Voltage / Low-Power) - a traditional system fitted with a 42-volt battery marketed as a "mild" hybrid.

By strictly following this definition of hybrid: "Something of mixed origin or composition", this type doesn't qualify at all since there is only a single source of propulsion. Realistically, a vehicle can't be a called hybrid unless at a minimum it shuts off the engine after stopping, has regenerative braking, and has an electric-motor that provides some thrust to the wheels.

The increased voltage offers rapid engine startup and the ability to run certain components on electricity instead of depending on power from the engine.


ASSIST

Type II (High-Voltage / Low-Power) - a system with a small battery-pack and small electric-motor that provides peak power for the engine during periods of acceleration.

Shuts off the engine when the vehicle stops.

Provides thrust with an electric motor.

Recaptures energy when the vehicle slows to charge the battery-pack.


FULL

Type III (High-Voltage / High-Power) - a system with a large battery-pack and large electric motor that provide a variety of combustion & electric propulsion options.

Shuts off the engine when the vehicle stops.

Recaptures energy when the vehicle slows to charge the battery-pack.

Propels the vehicle using all 3 methods at various times: Engine-Only, Motor-Only, Engine & Motor.

Provides electricity to a thrust-motor on-the-fly at times, rather than always drawing from the battery-pack.

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[RSnyder]

Actually, Honda and Toyota have been leapfrogging each other with each model built. This is because electric hybrid technology is so new both companies are still on the steep part of the learning curve. Expect continued big improvements from both companies.

In a series type hybrid when ever the vehicle is in motion the gas engine is running

It doesn't have to be. In the Honda's the engine may be spinning, but not necessarily receiving fuel. One could easily imagine a series hybrid with a transmission and/or clutch that allowed disconnect when the engine was not needed.