Perhaps it would help to clarify the somewhat confused understanding and difficulties in convaying the ideas behind various "Hybrid vehicles" by more accurately defining the specific aspects of such vehicles employing multiple technologies. The aspects which are Hybrid in nature could include but are not limited to Powered, Fueled, and/or Storage. So when categorizing a Hybrid vehicle one should mention which technologies (ie: GAS/ICE, Diesel/ICE, NG/ICE, LPG/ICE. H2/ICE, Electricity/Batteries/Motors, Hydrogen/Fuel Cell/Motors, Human/Peddles) are employed and the nature of their use. Such as Gas-Electric Powered or Diesel-Hydrogen Fueled.
There are an ever growing variety of Hybrid vehicle types comming into production, most of which are Gas-Electric Powered such as the Honda Insight and Toyota Prius.
Gas-Electric Powered vehicles such as the vast majority of current production Hybrid Electric Vehicles (HEVs) use gassoline via an ICE, and electricity from batteries charged by the ICE to power a motor(s). Even regen is the result of kinetic energy imparted entirely by gas and the ICE. So, most accurately their motive power is provided in a hybrid manner.
The Toyota, Honda, and Ford methods of implamentation fit this catagorie perfectly as they are Hybrid Powered but not Hybrid Fueled. 'Hybrids' are not Electric vehicles (EVs) as they do not use electricity as an external fuel source. Rather they are more closely related to traditional gas vehicles with large intigrated starter/alternator devices capable of performing new electric vehicle trick.
Not since the implamentation of the electric starter have such Battery Electric Vehicle (BEV) features been seen in so many production vehicles. Features such as never wastefully idling, high bi-directionally motor and battery effeciency (ie: regenerative braking), aswell as simplicity and versitility. Unfortunently the most important and perhaps timely desirable feature has not been made available, that being the ease and energy independance of plugging into domestic and potentially renewable or even home grown electric fuel sources.
Gas-Electric Fueled vehicles or Plug-in Hybrid Electric Vehicles (PHEVs) are vehicles which can use either gassoline via an ICE or electricity, from the grid or other sources, via a battery and motor. These can use either fuel sources in a hybrid manner with their respective conversion devices to provide propulsion. So they are most accurately Hybrid Fueled which implies that they also be Hybrid Powered.
Diesel-Electric Powered vehicles such as GM's new hybrid transit busses which runs only on diesel fuel. Diesel-electric locomotives may also fit this catagorie although most lack an accumulator or battery pack for cacheing electrical energy, unlike these [1] [2].
Diesel-Electric Fueled vehicles such as diesel transit busses which can also be fueled from overhead power wired.
Gas-LPG-NG Fueled vehicles such as existing Flexible-fuel vehicles use a single conversion device, usuaily an engine, which can run on multiple fuels. Such vehicles are Hybrid Fueled but not Hybrid Powered.
Human Fueled vehicles such as Electric-Bikes which can be fueled by electricity or by food consumed by the person who peddles the bike. Human-gas hybrid vehicles such as mopeds with peddles have also been produced.
It might also be noted that the ICE may be substituted for any thermo-dynamic conversion device burning any combustable gassious or liquid fuel. This might include other IC Engines such as Micro Turbine or External Combustion like Stirling engines or Steam Engines. Any of which may use gassoline, diesel, NG, LPG, Hydrogen, coal, or any other combustable fuels. The important distinction is that such devices are onboard the vehicle, and their fuels delivered from some external source. It should be noted that all such devices are limited to about 30% conversion effeciency durring which they convert naturally occuring and finite well ordered HC chains into lower order CO2 gasses which may be of concern when converted in such quantities as we do today.
In the case of the electric portion of the hybrid fueled vehicle, electricity is the fuel which is transfered to the vehicle from some external source. Most commonly this source is the electric grid and although it's wise to consider the sources for both combustion fuels and grid electricity it is also important to realize that combustibles are primarily limited to non-renewable resources while grid power tends to vary in it's source and must eventually move to more systainable natural resources. One should be carefull when compairing the two sides of such vehicles to either include or exclude both systems upstream and downstream 'costs'. Compare the entire cycle or simply the vehicle itself. Such is the case with homes and industry using grid electricity which may or may not already be renewable, but which are not nessecarliy required to and could very well collect their own sustainable energy. Similar is the case with an electric fueled vehicles which is not limited to grid electricity for it's external fuel source and also has almost no downstream pollution. Also consider that having a long energy payback on a systainable technology is far better than perpetually having no payback from a resource which is out of your controll and finite in nature.