With the various tax incentives on offer, and increasing concern about both pollution and future fuel prices, it is not hard to see why HybridVehicles are becoming more popular.

Most of us know by now that a Hybrid Vehicle has two sources of power;an electric motor and the good ol' Internal Combustion Engine (ICE).However, most people don't know much beyond that so let's go deeper:let's cut through the jargon and have a look at how Hybrid Vehiclesactually work.

Hybrid vehicles are usually based on two main designs; a paralleldesign, or a series design.

With a parallel design, the electric motor and ICE are both connecteddirectly to the vehicle's wheels. The ICE is used for normal driving;the electric motor provides additional power during acceleration, hillclimbs and other occasions of high demand.

With a series design, the ICE is connected to a generator which is usedto charge the batteries. It is the batteries which actually power thewheels via the electric motor.

Some hybrid vehicles use the series design at low speeds, and theparallel design for highway driving and acceleration.

Regenerative braking: normally the deceleration of a vehicle is wastedenergy; not so with Hybrids. Hybrids can use regenerative braking tocapture and store the energy lost in slowing down the vehicle aselectricity. The electricity can later be used to propel the vehicle.This increases the overall efficiency of the vehicle as energy that wasotherwise wasted is being stored and used again later.

Also energy that would otherwise be wasted while idling or cruising canalso be stored for later use. While cruising the ICE uses a lot of fuelin proportion to the actual work going into driving the wheels. Thismakes it particularly inefficient at those times. To increase efficiencysome of the output from the ICE is fed to a generator to charge thebatteries when the vehicle is cruising or travelling downhill.

Another clever trick is that the electric motor normally used to drivethe wheels can be used as the generator. This is how the regenerativebraking process, and the system for charging the battery during engineidling, generate electricity. At those times the electric motor is notneeded for propulsion, therefore, the ability of an electric motor tooperate in 'generator' mode is utilised so that a separate generator isnot required.

Vehicles which use the parallel or series design are sometimes known asFull Hybrids. Other types of Hybrids such as the Assist Hybrid and MildHybrid are basically just normal vehicles with a bit of electrical powersupplied at crucial moments. They may also offer Regenerative Braking.However, this kind of vehicle only provides about a 10% increase in fueleconomy and it is open to question as to whether the extra complexity isworthwhile.

Is the future of hybrid diesel?

The future of hybrids may very well lie in the diesel motor. Dieselengines operate at higher efficiency than petrol engines so deliver moremiles to the gallon, plus they are more reliable. Their maindisadvantage has always been poor acceleration, but in a hybrid this isnot an issue as it can be offset with extra propulsion from the electricmotor.

In addition, diesel engines can run on biofuels such as vegetable oiland the like. Such fuels are relatively clean and are not the dirtystuff often associated with diesel propulsion. Biofuels can be obtainedin a sustainable way and the costs are relatively independent of oilproduction and oil prices.

The combination of reliability, fuel economy (prototypes have achievedover 110 mpg US fuel economy) and sustainable sources of fuel, makes thediesel-engine based hybrids not only likely, but inevitable. This willhopefully give us breathing space till fuel cell technology matures.

Should you Buy a Hybrid Vehicle?

Here are some resources to help you decide:

You can check out this comparison char http://go.ucsusa.org/hybridcenter/compare_chart.cfm which will helpyou compare some hybrids with non-hybrids and a reference list of allFederal and State incentives for prospective hybrid owner http://go.ucsusa.org/hybridcenter/incentives.cfm .

Some topical articles; Buyers of hybrid cars get a pleasant surpris http://www.rocklintoday.com/news/templates/automotive_news.asp?articleid=3110&zoneid=1and one persons experience of the Cost of Owning a Hybrid ca http://www.hybridcars.com/blogs/sans-suv/apples-oranges.

Consumer Reports have now admitted that they made an error when theysaid owners of hybrid vehicles would pay more than buyers of comparablegasoline-only vehicles over their lifetime of ownership. Owners of theToyota Prius and Honda Civic hybrid http://www.hybridcars.com/news/news.php?news_id=832 do save money, themagazine now says.

If you want more in-depth technical information try What is a HybridElectric Vehicle?http://www.eere.energy.gov/cleancities/hev/what_is_hev.html/ whichincludes a nice simple overview of hybrid vehicle desig http://www.eere.energy.gov/cleancities/hev/hev_components.html and thepage Hybrid Electric Vehicle http://www.nrel.gov/vehiclesandfuels/hev/hevs.html has clear technicalexplanations.

Wikipedia has a well written Hybrid vehicl http://en.wikipedia.org/wiki/Hybrid_car entry which includes bothtechnical and ecological issues.

If all that is not enough for you try the Hybrid Electric Vehicle blo http://hybridblog.typepad.com which has lots of good info and links.