A hybrid electric vehicle (HEV) is a vehicle which combines a conventional propulsion system with an on-board rechargeable energy storage system (RESS) to achieve better fuel economy than a conventional vehicle without being hampered by range from a charging unit like a battery electric vehicle, which uses batteries charged by an external source. The different propulsion power systems may have common subsystems or components.

Regular HEVs most commonly use an internal combustion engine (ICE) and electric batteries to power electric motors. Modern mass produced HEVs prolong the charge on their batteries by capturing kinetic energy via regenerative braking, and some HEVs can use the combustion engine to generate electricity by spinning an electrical generator (often a motor-generator) to either recharge the battery or directly feed power to an electric motor that drives the vehicle. Many HEVs reduce idle emissions by shutting down the ICE at idle and restarting it when needed. An HEV's engine is smaller and may be run at various speeds, providing more efficiency.

HEVs became widely available to the public in the late 1990s with the introduction of the Honda Insight and Toyota Prius. HEVs are viewed by some automakers as a core segment of the next future automotive market.^[1] An article for the July-August 2007 issue of THE FUTURIST magazine titled "Energy Diversity as a Business Imperative"^[2] included plug-in hybrid vehicles. GM vice president for environment and energy Elizabeth Lowery is quoted as saying, "Today, we are embracing multiple energy sources because there is no single answer available for the mass market…"^[3]

The variety of hybrid electric designs can be differentiated by the structure of the hybrid vehicle drivetrain, the fuel type and the mode of operation.

In 2007, several manufacturers have announced that vehicles will use aspects of hybrid electric technology to reduce fuel consumption without the use of the hybrid drivetrain. Regenerative braking can be used to recapture energy and stored to power electrical accessories, such as air conditioning. Shutting down the engine at idle can also be used to reduce fuel consumption and reduce emissions without the addition of a hybrid drivetrain. In both cases, some of the advantages of hybrid electric technology are gained while additional cost and weight may be limited to the addition of larger batteries and starter motors. There is no standard terminology for such vehicles, although they may be termed mild hybrids.

The 2000s saw development of plug-in hybrid electric vehicles (PHEVs), which can be recharged from the electrical power grid and do not require conventional fuel for short trips. The Renault Kangoo was the first production model of this design, released in France in 2003.

Gasoline engines are used in most hybrid electric designs, and will likely remain dominant for the foreseeable future. While petroleum-derived gasoline is the primary fuel, it is possible to mix in varying levels of ethanol created from renewable energy sources. Like most modern ICE-powered vehicles, HEVs can typically use up to about 15% bioethanol. Manufacturers may move to flexible fuel engines, which would increase allowable ratios, but no plans are in place at present.

Diesel-electric HEVs use a diesel engine for power generation. Diesels have advantages when delivering constant power for long periods of time, suffering less wear while operating at higher efficiency. The diesel engine's high torque, combined with hybrid technology, may offer substantially improved mileage. Most diesel vehicles can use 100% pure biofuels (biodiesel), so they can use but do not need petroleum at all for fuel (although mixes of biofuel and petroleum are more common, and petroleum may be needed for lubrication). If diesel-electric HEVs were in use, this benefit would likely also apply. Diesel-electric hybrid drivetrains have begun to appear in commercial vehicles (particularly buses); as of 2007, no light duty diesel-electric hybrid passenger cars are currently available, although prototypes exist. Peugeot is expected to produce a diesel-electric hybrid version of its 308 in late 2008 for the European market.^[4]

PSA Peugeot Citroën has unveiled two demonstrator vehicles featuring a diesel-electric hybrid drivetrain: the Peugeot 307, Citroën C4 Hybride HDi and Citroën C-Cactus.^[5] Volkswagen made a prototype diesel-electric hybrid car that achieved 2 L/100 km (140 mpg_‑imp; 120 mpg_‑US) fuel economy, but has yet to sell a hybrid vehicle. General Motors has been testing the Opel Astra Diesel Hybrid. There have been no concrete dates suggested for these vehicles, but press statements have suggested production vehicles would not appear before 2009.

Robert Bosch GmbH is supplying hybrid diesel-electric technology to diverse automakers and models, including the Peugeot 308.^[6]

So far, production diesel-electric engines have mostly just appeared in mass transit buses.

Fedex, along with Eaton Corp. in the USA and Iveco in Europe, has begun deploying a small fleet of Hybrid diesel electric delivery trucks.^[7] As of October 2007 Fedex now operates more than 100 diesel electric hybrids in North America, Asia and Europe.^[8]

In some cases, manufacturers are producing HEVs that use the added energy provided by the hybrid systems to give vehicles a power boost, rather than significantly improved fuel efficiency compared to their traditional counterparts.^[9] The trade-off between added performance and improved fuel efficiency is partly controlled by the software within the hybrid system and partly the result of the engine, battery and motor size. In the future, manufacturers may provide HEV owners with the ability to partially control this balance (fuel efficiency vs. added performance) as they wish, through a user-controlled setting.^[10] Toyota announced in January, 2006 that it was considering a "high-efficiency" button.

One can buy a stock hybrid or convert a stock petroleum car to a hybrid electric vehicle using an aftermarket hybrid kit .^[11]

Benefits of the hybrid electric design include:

Fuel consumption

Current HEVs reduce petroleum consumption (compared to otherwise similar conventional vehicles) primarily by using three mechanisms:
a) Reducing wasted energy during idle/low output, generally by turning the ICE off;
b) Recapturing waste energy (i.e. regenerative braking);
c) Reducing the size and power of the ICE, and hence inefficiencies from under-utilization, by using the added power from the electric motor to compensate for the loss in peak power output from the smaller ICE.

Any combination of these three primary hybrid advantages may be used in different vehicles to realize different fuel usage, power, emissions, weight and cost profiles. The ICE in an HEV can be smaller, lighter, and more efficient than the one in a conventional vehicle, because the combustion engine can be sized for slightly above average power demand rather than peak power demand. The drive system in a vehicle is required to operate over a range of speed and power, but an ICE has its highest efficiency is in a narrow range of operation, making conventional vehicles inefficient. In contrast, in most HEV designs, the ICE operates closer to its range of highest efficiency more of the time. The power curve of electric motors is better suited to variable speeds and can provide substantially greater torque at low speeds compared with internal-combustion engines. The greater fuel economy of HEVs has implication for reduced petroleum consumption and vehicle air pollution emissions worldwide^[12]

Durability

Reduced wear on the gasoline engine, particularly from idling with no load. Reduced wear on brakes from the regenerative braking system use.

There's no definitive word on replacement costs of the batteries because they are almost never replaced. According to Toyota, since the Prius first went on sale in 2000, they have not replaced a single battery for wear and tear.^{[citation needed]}

Environmental impact

Reduced noise emissions resulting from substantial use of the electric motor at idling and low speeds, leading to roadway noise reduction,^[13] in comparison to conventional gasoline or diesel powered engine vehicles, resulting in beneficial noise health effects (although road noise from tires and wind, the loudest noises at highway speeds from the interior of most vehicles, are not affected by the hybrid design alone). Note, however, that this is not always an advantage; for example, people who are blind or visually-impaired, and who rely on vehicle-noise while crossing streets, find it more difficult to do safely.[1] Reduced air pollution emissions due to lower fuel consumption, leading to improved human health with regard to respiratory and other illness. Pollution reduction in urban environments may be particularly significant due to elimination of idle-at-rest.

One common misconception is: "However, one must remember the environmental stamp of HEV batteries, which must be replaced on a regular basis and are treated as extremely hazardous waste." This is not entirely true. Battery toxicity is a concern, although today's hybrids use NiMH batteries, not the environmentally problematic rechargeable nickel cadmium. "Nickel metal hydride batteries are benign. They can be fully recycled," says Ron Cogan, editor of the Green Car Journal. Toyota and Honda say that they will recycle dead batteries and that disposal will pose no toxic hazards. Toyota puts a phone number on each battery, and they pay a $200 "bounty" for each battery to help ensure that it will be properly recycled.

In 1901, while employed at Lohner Coach Factory, Ferdinand Porsche designed the "Mixte", a series-hybrid vehicle based off his earlier "System Lohner-Porsche" electric carriage. The Mixte broke several Austrian speed records, and also won the Exelberg Rally in 1901 with Porsche himself driving. The Mixte used a gasoline engine powering a generator, which in turn powered electric hub motors, with a small battery pack for reliability. It had a range of 50 km, a top speed of 50 km/h and a power of 5.22 kW during 20 minutes.

The 1915 Dual Power, made by the Woods Motor Vehicle electric car maker, had a four-cylinder ICE and an electric motor. Below 15 mph (25 km/h) the electric motor alone drove the vehicle, drawing power from a battery pack, and above this speed the "main" engine cut in to take the car up to its 35 mph (55 km/h) top speed. About 600 were made up to 1918.^[14]

A more recent working prototype of the HEV was built by Victor Wouk (one of the scientists involved with the Henney Kilowatt, the first transistor-based electric car). Wouk's work with HEVs in the 1960s and 1970s earned him the title as the "Godfather of the Hybrid".^[15] Wouk installed a prototype hybrid drivetrain (with a 16 kW electric motor) into a 1972 Buick Skylark provided by GM for the 1970 Federal Clean Car Incentive Program, but the program was stopped by the United States Environmental Protection Agency (EPA) in 1976 while Eric Stork, the head of the EPA at the time, was accused of a prejudicial coverup.^[16]

The regenerative braking system, the core design concept of most production HEVs, was developed by electrical engineer David Arthurs around 1978 using off-the shelf components and an Opel GT. However the voltage controller to link the batteries, motor (a jet-engine starter motor), and DC generator was Arthurs'. The vehicle exhibited Template:Mpg fuel efficiency and plans for it (as well as somewhat updated versions) are still available through the Mother Earth News web site. The Mother Earth News' own 1980 version claimed nearly Template:Mpg.

In 1989, Audi produced its first iteration of the Audi Duo (or Audi 100 Avant duo) experimental vehicle, a plug-in parallel hybrid based on the Audi 100 Avant quattro. This car had a 12.6 bhp Siemens electric motor which drove the rear wheels. A trunk-mounted nickel-cadmium battery supplied energy to the motor that drove the rear wheels. The vehicle's front wheels were powered by a 2.3-litre five-cylinder engine with an output of 136 bhp. The intent was to produce a vehicle which could operate on the engine in the country and electric mode in the city. Mode of operation could be selected by the driver. Just ten vehicles are believed to have been made; one drawback was that due to the extra weight of the electric drive, the vehicles were less efficient when running on their engines alone than standard Audi 100s with the same engine.

Two years later, Audi unveiled the second duo generation - likewise based on the Audi 100 Avant quattro. Once again this featured an electric motor, a 28.6 bhp three-phase machine, driving the rear wheels. This time, however, the rear wheels were additionally powered via the Torsen differential from the main engine compartment, which housed a 2.0-litre four-cylinder engine.

The Bill Clinton administration initiated the Partnership for a New Generation of Vehicles (PNGV) program on 29 September, 1993 that involved Chrysler, Ford, General Motors, USCAR, the DoE, and other various governmental agencies to engineer the next efficient and clean vehicle.^[17] The NRC cited automakers’ moves to produce HEVs as evidence that technologies developed under PNGV were being rapidly adopted on production lines, as called for under Goal 2. Based on information received from automakers, NRC reviewers questioned whether the “Big Three” would be able to move from the concept phase to cost effective, pre-production prototype vehicles by 2004, as set out in Goal 3.^[18] The program was replaced by the hydrogen-focused FreedomCAR initiative by the George W. Bush administration in 2001,^[19] an initiative to fund research too risky for the private sector to engage in, with the long-term goal of developing effectively carbon emission- and petroleum-free vehicle

Automotive hybrid technology became successful in the 1990s when the Honda Insight and Toyota Prius became available. These vehicles have a direct linkage from the ICE to the driven wheels, so the engine can provide acceleration power.

The Prius has been in high demand since its introduction. Newer designs have more conventional appearance and are less expensive, often appearing and performing identically to their non-hybrid counterparts while delivering 40% better fuel efficiency. The Honda Civic Hybrid appears identical to the non-hybrid version, for instance, but delivers about Template:Mpg. The redesigned 2004 Toyota Prius improved passenger room, cargo area, and power output, while increasing energy efficiency and reducing emissions. The Honda Insight, while not matching the demand of the Prius, stopped being produced after 2006 and has a devoted base of owners. Honda has also released a hybrid version of the Accord.

An R.L. Polk survey of 2003 model year cars showed that hybrid electric car registrations in the United States rose to 43,435 cars, a 25.8% increase from 2002 numbers.^{[citation needed]} California had the most HEVs registered: 11,425. The proportionally high number may be partially due to the state's higher gasoline prices and stricter emissions rules, which HEVs generally have little trouble passing.

Honda, which offers Insight, Civic and Accord models, sold 26,773 HEVs in the first 11 months of 2004. Toyota has sold a cumulative 306,862 HEVs between 1997 and November 2004, and Honda has sold a total of 81,867 HEVs between 1999 and November 2004.^[20]

Audi was the first European car manufacturer to put in 1997 a hybrid vehicle into series production, the third generation Audi duo, then based on the A4 Avant.^[21]

2005 saw the first hybrid electric sport utility vehicle (SUV) released, the Ford Escape Hybrid. Toyota and Ford entered into a licensing agreement in March 2004 allowing Ford to use 20 patents from Toyota related to hybrid technology, although Ford's engine was independently designed and built. In exchange for the hybrid licenses, Ford licensed patents involving their European diesel engines to Toyota. Toyota announced model year 2005 hybrid electric versions of the Toyota Highlander and Lexus RX 400h with 4WD-i, which uses a rear electric motor to power the rear wheels negating the need for a differential. Toyota also plans to add hybrid drivetrains to every model it sells in the coming decade.^{[citation needed]}

In 2007, Lexus released a hybrid electric version of their GS sport sedan dubbed the GS450h, with "well in excess of 300hp".^{[citation needed]} The 2007 Camry Hybrid became available in Summer 2006 in the United States and Canada. Nissan announced the release of the Altima hybrid (technology supplied by Toyota) in 2007.Hybrid cars see record sales.^[22]

Manufacturers are going to introduce 15 new hybrids in 2008^[23]

In 2007 appears the DoE´s Plug-in Hybrid Electric Vehicle Plan and the PHEV mass-production race.

eCycle Inc produces series diesel-electric motorcycles, with a top speed of 80 mph (130 km/h) and a target retail price of $5500.^[24]

A number of manufacturers currently produce hybrid electric automobiles and light trucks, including Ford, General Motors, Honda, Mazda, Mercury, Nissan, PSA (Peugeot-Citröen), Renault, and Toyota. Other types of HEVs are manufactured including Microhybrids (small hybrid electric city cars) like the Aptera. Diesel-electric hybrid vehicles such as Citroën C-Cactus concept car and GM's Chevy Volt plug-in hybrid may soon see mass-production.

Combined sales of HEVs in the U.S. rose 54% in February 2007 to more than 22,998 units, up 52% from the results in February 2006. The figures do not include sales of GM HEVs, which the automaker does not yet break out, but do reflect the addition of the Nissan Altima Hybrid, now sold in eight states.^[25] An estimated 180,000 HEVs were sold in the U.S. in first half of 2007, or 3% of car sales during that period.^[26]

HEVs (and specially plug-ins) may be particularly appropriate for use as taxicabs, as in many locations they are used in predominantly urban environments; have intensive operating schedules, maximizing fuel savings over the life of the vehicle; may spend considerable periods of time at idle, where the hybrid electric engine may allow for the ICE to be shut off (while retaining use of electrical accessories); and can recharge batteries at taxicab stands.

New York City started converting its taxi fleet to hybrids in 2005,^[27] with 375 active as of July, 2007. The mayor plans to convert 20% of the remaining 13,000 taxis each year.

San Francisco intends to convert its entire fleet to hybrid or Compressed natural gas vehicles by 2008.^[28]

Hybrid technology for buses has seen increased attention since recent battery develpments decreased battery weight significantly. Drivetrains consist of conventional diesel engines and gas turbines. Some designs concentrate on using car engines, recent designs have focused on using conventional diesel engines already used in bus designs, to save on engineering and training costs. Several manufacturers are currently working on new hybrid designs, or hybrid drivetrains that fit into existing chassis offerings without major re-design. A challenge to hybrid buses may still come from cheaper lightweight imports from the former Eastern block countries or China, where national operators are looking at fuel consumption issues surrounding the weight of the bus, which has increased with recent bus technology innovations such as glazing, air conditioning and electrical systems. A hybrid bus can also deliver fuel economy though through the hybrid drivetrain. Hybrid technology is also being promoted by environmentally concerned transit authorities.

In 2003 GM introduced a hybrid diesel-electric military (light) truck, equipped with a diesel electric and a fuel cell auxiliary power unit. Hybrid electric light trucks were introduced in 2004 by Mercedes Benz (Sprinter) and Micro-Vett SPA (Daily Bimodale). International Truck and Engine Corp. and Eaton Corp. have been selected to manufacture diesel-electric hybrid trucks for a US pilot program serving the utility industry in 2004. In mid 2005 Isuzu introduced the Elf Diesel Hybrid Truck on the Japanese Market. They claim that approximately 300 vehicles, mostly route buses are using Hinos HIMR (Hybrid Inverter Controlled Motor & Retarder) system. In 2007, height petroleum price means a hard sell for hybrid trucks^[29] and appears the first U.S. production hybrid truck (International DuraStar Hybrid).^[30]

Other vehicles are:

• Big mining machines like the Liebherr T 282B dump truck or Keaton Vandersteen LeTourneau L-2350 wheel loader are powered that way.
• Also NASA's huge Crawler-Transporters are propelled diesel-electrically.
• Mitsubishi Fuso Canter Eco Hybrid is a diesel-electric commercial truck.

Hino Motors (a Toyota subsidiary) has the world's first production hybrid electric truck in Australia (110 kW (150 hp)^* diesel engine plus a 23 kW (31 hp)^* electric motor).^[31]

Other hybrid petroleum-electric truck makers are DAF Trucks, MAN AG with MAN TGL Series, Nissan Motors and Renault Trucks with Renault Puncher.

Hybrid electric truck technology and powertrain maker: ZF Friedrichshafen.

The United States Army's manned ground vehicles of the Future Combat System all use a hybrid electric drive consisting of a diesel engine to generate electrical power for mobility and all other vehicle subsystems. Other military hybrid prototypes include the Millenworks Light Utility Vehicle, the International FTTS, and the Shadow RST-V.

In May 2003 JR East started test runs with the so called NE (new energy) train and validated the system's functionality (series hybrid with lithium ion battery) in cold regions. In 2004, Railpower Technologies had been running pilots in the US with the so called Green Goats,^[32] which led to orders by the Union Pacific^[33] and Canadian Pacific^[34] Railways starting in early 2005.

Railpower offers hybrid electric road switchers,^[35] as does GE.^[36] Diesel-electric locomotives may not always be considered HEVs, not having energy storage on board, unless they are fed with electricity via a collector for short distances (for example, in tunnels with emission limits), in which case they are better classified as dual-mode vehicles.

Produces marine hybrid propulsion:

• eCycle Inc.^[37]
• Solar Sailor Holdings

HEVs are more expensive (the so-called "hybrid premium") than traditional ICE vehicles (ICEV), due to extra batteries, more electronics and in some cases other design considerations. The trade-off between higher initial cost and lower fuel costs (often referred to as the payback period) is dependent on usage - miles traveled, or hours of operation, fuel costs, and in some cases, government subsidies. Traditional economy vehicles may result in a lower direct cost for many users (before consideration of any externality).

Consumer Reports ran an article in April 2006 stating that HEVs would not pay for themselves over 5 years of ownership. However, this included an error with charging the "hybrid premium" twice.^[38] When corrected, the Honda Civic Hybrid and Toyota Prius did have a payback period of slightly less than 5 years.^[39] This includes conservative estimates with depreciation (seen as more depreciation than a conventional vehicle, although that is not the current norm) and with gas prices. In particular, the Consumer Reports article assumed $2/U.S. gallon for 3 years, $3/U.S. gallon for one year and $4/U.S. gallon the last year. As recent events have shown, this is a volatile market and hard to predict. For 2006, gas prices ranged from low $2 to low $3, averaging about $2.60/U.S. gallon.

A January 2007 analysis by Intellichoice.com shows that all 22 currently available HEVs will save their owners money over a five year period. The most savings is for the Toyota Prius, which has a five year cost of ownership 40.3% lower than the cost of comparable non-hybrid vehicles.^[40]

A report in the Greeley Tribune says that over the five years it would typically take for a new car owner to pay off the vehicle cost differential, a hybrid Camry driver could save up to $6,700 in gasoline at current gasoline prices, with hybrid tax incentives as an additional saving.^[41]

In countries with incentives to fight against global warming and contamination and promote vehicle fuel efficiency, the pay-back period can be immediate and ICEV can cost more than hybrid because they generate more pollution.

Plug-in hybrids can also be recharged using an electric outlet.

In order to encourage the purchase of HEVs, several incentives and ecotaxes have been made into law.

In the Netherlands, the Vehicle Registration Tax (VRT), payable when a car is sold to its first buyer, can earn the owner of an HEV a discount up to €6,000. In the Republic of Ireland, a 50% reduction in VRT applies, which normally amounts to 25% of the market value of a car.

Drivers of HEVs in the United Kingdom benefit from the lowest band of vehicle excise duty (car tax), which is based on carbon dioxide emissions. In central London, these vehicles are also exempt from the £8 daily London congestion charge.^[42] Due to their low levels of regulated emissions, the greenest cars are eligible for 100% discount under the current system. To be eligible the car must be on the current Power Shift Register.^[43] At present, these include the cleanest LPG and natural gas cars and most hybrid-, battery- and fuel cell-electric vehicles.

Residents in Ontario, Canada can claim a rebate on the Provincial Retail Sales Tax of up to $2,000 CDN on the purchase or lease of a hybrid electric vehicle.^[44] Ontario recently announced a new green license plate for hybrid car users and will announce a slew of benefits that go along with it in 2008.^[45] Residents in British Columbia are eligible for a 100% reduction of sales tax up to a maximum of $2,000 if the hybrid electric vehicle is purchased or leased before April 1, 2011 (extended in 2007/2008 budget from March 31, 2008 and expanded from a maximum of only $1,000 from April 1, 2008 to March 31, 2009, at which point the concession was scheduled to expire.)^[46]The Canadian federal government recently began offering rebates in March 2007 of $1000-$2000. Generally cars getting 6.5 L/100km or better and light trucks getting 8.3 L/100km or better will quailify.^[47]

Diesel-electric and gasoline-electric hybrids are not grouped under the electric fuel category because the input fuel is diesel or gasoline rather than an alternative transportation fuel. DOE, which has EPACT92 implementation authority, ruled that diesel-electric and gasoline-electric hybrids are not "alternative fuel vehicles."^[48]

The purchase of hybrid electric cars qualifies for a federal income tax credit up to $3,400 on the purchaser's Federal income taxes. The tax credit is to be phased out two calendar quarters after the manufacturer reaches 60,000 new cars sold in the following manner: it will be reduced to 50% ($1700) if delivered in either the third or fourth quarter after the threshold is reached, to 25% ($850) in the fifth and sixth quarters, and 0% thereafter. Many states give additional tax credits to hybrid electric car buyers. Also this can help us to use less gasoline.

• Certain states (e.g., New York, California, Virginia, and Florida) allow singly-occupied HEVs to enter the HOV lanes on the highway. Initially, the Federal Highway Administration ruled that this was a violation of federal statute^[49] until August 10 2005 when George W. Bush signed the Transportation Equity Act of 2005 into law.
• Some states, e.g. California, exempt hybrid electric cars from the biennial smog inspection, which costs over $50 (as of 2004).
• The city of San Jose, California issued a free parking tag until 2007 when it became issued for a fee annually for hybrid electric cars that were purchased at a San Jose dealership. The qualified owners do not have to pay for parking in any city garage or road side parking meters.
• City of Los Angeles, California offers free parking to all HEVs starting on 1 October 2004. The experiment is an extension to an existing offer of free parking for all pure electrical vehicles.
• In October, 2005, the City of Baltimore, Maryland started to offer discount on monthly parking in the city parking lots, and is considering free meter parking for HEVs. On 3 November 2005, the Boston Globe reports that the city council of Boston is considering the same treatment for hybrid electric cars.
• Annual vehicle registration fees in the District of Columbia are half ($36) that paid for conventionally vehicles ($72).

AllianceBernstein projects that worldwide by 2030, 72% of the fleet and 85% of new cars will be hybrids (regular or plug-in hybrids).^[50]

Worldwide demand for hybrid-electric vehicles (HEVs) will advance rapidly to 4.0 million units in 2015. HEVs are expected to quickly penetrate the world light vehicle market in response to rising energy costs and increased emissions regulations worldwide.^[51]

Template:EnergyPortal

• ACT Hybrid Vehicle Authority
• Bivalent (engine)
• Comparison of Toyota hybrids
• List of hybrid vehicles
• Super Ultra Low Emission Vehicle
• Tribrid vehicle

• Template:Dmoz
• How hybrid cars work at HowStuffWorks
• Compare hybrid cars at FuelEconomy.gov
  • U.S. Federal Income Tax Deduction for Hybrids Placed in Service
• New York City Taxis to go all hybrid by 2012 2007-05-22
• GM Announces Chevrolet Volt Series Hybrid Concept Vehicle 2007-01-07
• Series, Parallel, and series-parallel systems animation by Union of Concerned Scientists
• Mother Earth News article from 1978 on the original regenerative braking hybrid car
• Folsom Technologies, Inc. Hybrid Hydraulic, Hybrid Electric, and CVT technologies
• Hybrid-Electric "Bus of the Future" Tested By Capital Metro.
• Toyota's hybrid cars information, HYBRID SYNERGY DRIVE
• Israel Mulls Hybrid Taxis
• FedEx to Launch Commercial Hybrid-Electric Vans from Iveco in Europe
• About FedEx Hybrid Electric Vehicle in the USA