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It's now been just over a decade since the first hybrids, the original Honda Insight and Toyota Prius, were introduced. After a slow start, rising fuel costs caused consumer interest to take off mid-decade. Today, most consumers have some idea of what a hybrid is, but many are unaware that hybrid systems from competing manufacturers have entirely different hardware and function in dramatically dissimilar ways. That's why, for instance, you can't drive a Honda Civic hybrid on electric power alone, but you can in a Prius. Even greater variations on the hybrid theme will become available in the next few years, as automakers attempt to reduce costs, improve efficiency, and steer clear of patents held by their competitors. How do you make sense of it all? Click below to launch our gallery.

  • Defining Hybrids- Hybrid systems are typically described as micro, mild or strong depending on the amount of electrical power available to drive the vehicle. The most basic function of hybrid systems is automatic start-stop to shut the engine down when the car stops. Preventing idling in this way conserves fuel and lowers emissions. In Europe there are a number of these micro-hybrids that really aren't hybrids at all because they only provide the start-stop function but no electric drive or regenerative braking capability.

  • Image Credit: Ford
  • Mild and Strong Hybrids
  • Mild and Strong Hybrids - The mild and strong hybrids add an electric boost or drive motor to the package. Since electric motors are generally able to produce electricity when they are driven mechanically, this also allows for regenerative braking. In these hybrids, lifting off the accelerator and coasting causes the wheels to turn the motor to produce electricity and recharge the battery. While this is happening it increases drag and the vehicle slows, just like it does under engine braking in a conventional vehicle. The battery powers the electric motor during acceleration or cruising. This cuts the workload on the gasoline engine and reduces its fuel consumption. In a mild hybrid, the motor typically has an output of 15 kilowatts or less, which is enough to provide boost and start-stop capability, but not enough to drive the vehicle on electricity alone. Strong hybrids typically have motor/generators with 30 kW or more, which allows them to be driven on electricity alone for short distances (1-2 miles) at speeds under 65 miles per hour.

  • Image Credit: GM
  • Parallel Hybrids - All the hybrids on the market today are so-called "parallel" hybrids, so named because multiple propulsion sources can drive the wheels at the same time. These systems consist of a conventional internal combustion engine combined with one or more electric motor/generator(s) and a battery. Let's take a look at representatives of each hybrid camp, and see how they differ.

  • Image Credit: Ford
  • Power-Split Strong hybrid
  • Power-Split Strong hybrid - Over the past 12 years Toyota has sold far more hybrid vehicles than all the other manufacturers combined, and as a result its power-split strong hybrid configuration is the most common type by a wide margin. The same basic hardware configuration is also used by Ford for the Escape and Fusion. GM's two-mode hybrids, though different in design, also fall under this category. Each of these systems consist of an electronically controlled, variable-ratio transmission with motor/generators integrated into the transmission case. The variable ratio gears allow torque output from the engine speed to be continuously adjusted relative to vehicle speed so that the electric motor torque can be seamlessly blended in when extra power is needed. In these strong hybrids, the electric components have enough power to propel the vehicle on battery power alone for limited distances. The electric drive speed varies from about 25 mph for the Chevrolet Tahoe hybrid to up to 47 mph for the Ford Fusion. Some enthusiasts have hacked the control software in the Prius allowing it to go up to 60 mph on electricity alone.
  • Image Credit: Toyota
  • Power-Split Strong hybrid, continued
  • Power-Split Strong hybrid, continued - Besides being highly efficient, electric motors have another important functional advantage over internal combustion engines. Motors produce their maximum torque from idle and basically maintain that torque through most of their operating range. When incorporated into a hybrid powertrain, this allows the engine designers to modify the behavior of the internal combustion engine for improved efficiency. Gasoline engines in conventional vehicles run on what is known as the Otto four-stroke cycle, while hybrids use the Atkinson cycle. The main difference between the Otto and Atkinson is that the intake valves close later in the cycle to reduce pumping losses. This makes Atkinson more fuel-efficient but produce less torque. Normally drivers wouldn't like the way this feels but the electric motor fattens up the combined torque curve. Power-split hybrids have proven to be efficient but the transmission integrated with the motors is mechanically complex and expensive to build.

  • Image Credit: Toyota
  • Engine-Mounted Mild Hybrid
  • Engine-Mounted Mild Hybrid - The 1999 Honda Insight was actually the second modern hybrid to come to market after the Prius (although it did beat the Toyota to U.S. by about six months). Honda has since used its hybrid architecture one each of its successive hybrid models. It's so-called "Integrated Motor Assist" uses a lower power motor mounted directly on the output end of the engine's crankshaft. When energized, the motor applies torque directly to the crankshaft upstream of the clutch. In 2005, GM briefly offered a similar system in its full-size pickups and BMW and Mercedes-Benz have jointly developed a system of their own that went on sale in late 2009. Because the motor is directly coupled to the engine and has lower output than a strong hybrid, these mild hybrids are unable to drive on electricity alone. Instead the motor provides extra boost and regenerative braking capability and also acts as the starter. While motor output is inadequate to drive the vehicle, it is sufficient to provide the torque needed to run the engine on an Atkinson cycle for improved efficiency. Since mild hybrids use less powerful motors, they consequently have smaller batteries as well.
  • Image Credit: Honda
  • Engine-Mounted Mild Hybrid, continued
  • Engine-Mounted Mild Hybrid, continued - These engine-mounted mild hybrids are less expensive to build than power-split systems and have the advantage of being modular. Separating the electric motor from the transmission makes it easier to adapt the technology to different vehicles by combining an internal combustion engine and electric motor with any type of gearbox including manuals (Honda CR-Z), conventional planetary gear automatics (BMW ActiveHybrid 7) and continuously variable transmissions (Honda Insight).
  • Image Credit: Honda
  • Transmission-Mounted Strong Hybrid
  • Transmission-Mounted Strong Hybrid - Several new strong hybrids from Hyundai, Volkswagen and Porsche are coming to market this year. Unlike the earlier strong systems, these new variants are in many ways closer to the Honda/Mercedes-Benz/BMW systems, with their electric motor/generator separated from the transmission internals. However, because the higher output motors are able to adequately drive the vehicle electrically, they are connected to the input side of the transmission.
  • Image Credit: Porsche
  • Transmission-Mounted Strong Hybrid, continued
  • Transmission-Mounted Strong Hybrid, continued - These systems use an automatically controlled clutch between the engine and electric motor that is opened up when the battery has sufficient power and the driver's acceleration demand is low or the vehicle is stopped. In the case of the Volkswagen/Porsche system, there is an additional clutch between the electric motor and transmission to help improve the smoothness of operation during shifts. Putting the motor at the input of the transmission allows it to spin at a lower speed so that it can provide electric drive at higher vehicle speeds for better highway economy. The 2011 Hyundai Sonata, Volkswagen Touareg and Porsche Cayenne hybrids can all cruise with the engine off at over 60 mph.
  • Image Credit: Porsche
  • Belt-Alternator-Starter Mild Hybrid
  • Belt-Alternator-Starter Mild Hybrid - GM offered a belt-alternator-starter (BAS) mild hybrid system in the Saturn Vue and Aura, as well the Chevrolet Malibu. Rather than having the electric motor feed power directly to the transmission input, GM developed a system with what looked like a conventional alternator. However, in addition to producing electricity, this alternator could also act as a drive motor.
  • Image Credit: GM
  • Belt-Alternator-Starter Mild Hybrid, continued
  • Belt-Alternator-Starter Mild Hybrid, continued - GM engineers added a second idler pulley to the drive belt, which allowed the alternator-motor to restart the engine after a stop and feed some extra torque to the engine crankshaft when the driver wanted more acceleration. Unfortunately, the first generation BAS hybrid only had a 5 kW output (about 6.7 horsepower) and a 36-volt nickel-metal-hydride battery, which limited its usefulness. At the 2008 Geneva Motor Show, GM announced a second-generation version of this system with a more powerful 15 kW (about 20 hp) alternator-motor and a lithium-ion battery. This system will debut in early 2011, likely on the Buick Regal.
  • Image Credit: GM
  • Through-the-Road Strong Hybrid
  • Through-the-Road Strong Hybrid - Through-the-road (TtR) hybrids are likely to be the least familiar to most drivers since there aren't any currently available for sale. Unlike all of the other hybrid systems described here, the engine and electric drive systems are completely independent in the vehicle. The name is derived from the way that power blending is handled "through the road." The first production TtR hybrids will go on sale in Europe in 2011 when Peugeot introduces this system in its 508 sedan and 3008 crossover. A typical TtR hybrid will have a front-engine driving the front wheels, with an electric motor mounted at the rear axle along with a battery somewhere in the back of the vehicle. In this way, the electric drive can provide instant on-demand, all-wheel-drive when extra power or traction is needed. At lower speeds, if the battery has enough charge, the system can also drive the car electrically by shifting the front transmission into neutral.
  • Image Credit: Peugeot
  • Through-the-Road Strong Hybrid, continued
  • Through-the-Road Strong Hybrid, continued - The advantage of a TtR hybrid is that the cost can be significantly lower because the conventional drivetrain can be essentially stock. Only the control software would need to be changed in order to allow engine shutoff at idle or lower speeds. All-wheel-drive can be achieved without having to run a driveshaft down the middle of the vehicle. On the other hand, the electric motor has to be separately packaged and a through-the-road hybrid might not be as efficient at as some of the other systems because it cannot capture as much kinetic energy during regenerative braking at the rear axle.
  • Image Credit: Peugeot


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  • 22 Comments
      • 1 Month Ago
      Good site with first bit of info that one type of hybrid can be used as a totally electric auto & another can't.
      • 1 Month Ago
      I recently went on line to get quotes for Auto insurance policies. My existing carriers rates have continued to escalate and I wanted to make sure they were competitive. As a result of my inquiry I was contacted and provided quotes by several sources. This company : ( http://biglnk.com/autoinsurancetips ) provided attractive quotes. I will tell you that they saved me a considerable amount of money. Car premiums went from $1335.00 to $904.00 I thought I could save money but never imaged that much. 5 minutes could save you $400!!!
      brian1russ
      • 1 Month Ago
      I'd like to know what the fuel economy of the Chevy Volt would be if you never plugged it in.
      Torrence
      • 1 Month Ago
      It makes me sick that all we see is how GREAT the imports are. I've been driving AMERICAN cars all my life [I'm 74] and have driven all over this beautiful country and have NEVER BROKEN DOWN or had any problems. You see, I take care of my autos and they take care of me. So, shove you imports....BUY AMERICAN you morons.
        david85719
        • 1 Month Ago
        @Torrence
        many imports are built in the good ol US of A. My toyota camry was build in Kentucky.. many of the AMERICAN car parts are built in foreign countries.. many US cars are built in Mexico and Canada..
      sixpackdan
      • 1 Month Ago
      Allow me to correct you.... Many import cars are "assymbled" here. Most of the parts come from out side the country ....OR from companys owned outside the US. They REALLY dont like doing buisness with americans. So thats why most of the suppliers are not american owned. Not all.....just most.
      Carol and Bobby
      • 1 Month Ago
      How many Nuclear Power Plants are we going to have to build to re-charge all of these limited range, 4-wheel examples of 'Amatuer Hour at the Drawing Board'? Obama wants green? O.K. - just wait until the first Reactor fails and the inability to charge your car becomes a way of life. Then, wait for the 'Green' A-holes to come out and say it was always a possibility, but ..... (ahem ...) THEIR most recent testing on fall-out shows that it will definitely be 'safe' to cook with. I don't know about anyone else, but this will ruin MY dinner for a few years. OH BOY, --- GREEN RADIATION!
      sixpackdan
      • 1 Month Ago
      Absolutly! buy a hybrid and distroy mother earth. Good god is ALL the car populus completly stupid. JUST because you save a few gallons of gas you morons think your saving the planet!!! B/S!!!! GET REAL the carbon foot print of hybrids is ABSOLUTLY stagering. Wake up and cut the crap. If your buying an over priced hybrid to feel good about yourself thats ALL your really doing. Those dam batteries and the associated systems punch up your carbon footprint to the hummer level!!!!! Get off your hi horse. If you REALLY want to impress me ride a bike or take public transportation. Drop the attitude.....your "saving" is a complete lie. I got a slightly modifiied Geo metro that get 60 mpg.....AND i dont have to drive like a douche to get that milage. Let me see ANY of your pos hybrids match that in EVERY day driving. My footprint is WAY smaller....jerks. Thats ok you will pay when you die. Mom earth is gona kick your azz.
      fkurtin
      • 1 Month Ago
      All are hybrids equal in the eyes of the public, as in they are all over priced and nothing but junk. Americans are getting sick and tired of this trash, including all the lies. I would not buy one if I did have that much cash.Every one of them have been a rip off so far, bragged up trash heap,nothing more
        • 1 Month Ago
        @fkurtin
        What a bunch of overpriced gas guzzling junks. My car running on CNG and comparing the cost to gasoline at almost $4 a gallon and I pay $.86 a gallon. Hmm, If I only guess without pulling out a calculator I get 4 times the MPG. So figure if I average 30 MPG at gasoline prices it should equate to 120 MPG on a bad day. Who believes the **** they write here. Go Green and switch to Compressed Natural Gas, You won't regret it.
        librayacht
        • 1 Month Ago
        @fkurtin
        Obviously this correspondent does not know anything about hybrids. I have had a Toyota Prius for several years and now have in excess of 55,000 miles on it. It has never been in the shop for other than regular maintenance. The car is technologically superb in all of its functions. The stereo and automatic climate control can be accessed through the touch screen display or from the steering wheel. It has fully automatic constant velocity transmission and everyone who travels in my car comments on how smooth the car moves and how quiet it is with no hint of a gear shift.
        In the winter my car averages 45.5 mpg and in the summer 43.2. I ran this car right through the expensive gas period and saved more than my payments. I do not save as much now gas is back to $2.80. I paid list price for my car which was $21,770 (no discounts available then) and I intend to run it for many more years.
        It is amazing that I can take four people in excellent comfort, with lots of rear legroom, to visit my daughter who lives 100 miles away and return for less than 5 gallons of gas. Try and do that in any other car!!!
        Until the US produces, or permits the import of, small diesel cars the strong hybrid will be the only economical alternative.
        fkurtin
        • 1 Month Ago
        @fkurtin
        not narrow minded, we need a hybrid but we need a real one that lasts longer than the payment, like any new vehicle ,they are designed to be worthless as soon as you pay it off, Consider this , they never want you not paying. Im still driving my 64 gmc 1/2 ton ,v-8,27 mpg and kicks azz
        • 1 Month Ago
        @fkurtin
        Just wanted to let you know that I saved a TON of money finding an insurance company through this website: ( http://bit.ly/CarInsurancePros ). I found one that saved me 57.5% on my premium - pretty amazing if you ask me.
        fkurtin
        • 1 Month Ago
        @fkurtin
        you feed a monster that is killing USA economy. I am libra also and can weigh things out without being forced to make a decision and cave in as you have, your car is junk, I'm a retired auto mech
        librayacht
        • 1 Month Ago
        @fkurtin
        What about all of the US produced hybrids such as the Ford Fusion, the Chevrolet Malibu, Escalade hybrid, Denali Hybrid etc etc. Are they also junk?. I am sure the world will be very happy that you have retired having such a narrow outlook.
      • 1 Month Ago
      We should all be thinking Http://www.hybridcarplace.com about getting a hybrid car.
      • 1 Month Ago
      All Americans don't always live in the U.S. so one has to use what is around. Can't do bicycle. Distance & dirt roads.Definitely no public transport. Keep really old car for trips to town & back & more modern one,(1990's) for distances. Was thinking of boosting 5kv solar power for a hybrid if possible.Am a newby to all this. Don't have one but if it's no good for the environment I'll just forget it. Maybe we'll all have to go back to horses & modern type buckboards with rubber tire wheels soon anyway.
      • 1 Month Ago
      I'VE OWNED AND DRIVEN FOR MANY MANY MILES THE 2ND, 3RD, AND 4TH GENERATION PRIUS (THE IST WAS IN JAPAN ONLY) WITH NO PROBLEMS! FUN TO DRIVE, LOTS OF ROOM, PLENTY OF ACCELERATION, AND DID 108 MPH ON DETROIT FREEWAY AND COULD HAVE GONE FASTER! AT 45 TO 49 MPG -- IT'S BEEN AND STILL IS OUR COUNTRY'S ANSWER TO THE OIL PROBLEM -- AT LEAST UNTIL SOMETHING BETTER IS MADE AVAILABLE. TRY IT AND SEE WHAT A GREAT CAR IT IS.
        sixpackdan
        • 1 Month Ago
        jack azz.....with NON of the battery b/s i get 60mpg with a slightly moded geo metro. You can guess where you can put your prius.
      • 1 Month Ago
      What a bunch of overpriced gas guzzling junks. My car running on CNG and comparing the cost to gasoline at almost $4 a gallon and I pay $.86 a gallon. Hmm, If I only guess without pulling out a calculator I get 4 times the MPG. So figure if I average 30 MPG at gasoline prices it should equate to 120 MPG on a bad day. Who believes the **** they write here. Go Green and switch to Compressed Natural Gas, You won't regret it.
        sixpackdan
        • 1 Month Ago
        And your storage capacity totaly sucks.....can you go on a 500 mile non stop ride? NO CNG is very clean and a pita to use because of the issues with filling and lack of places to fill up.
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