In the quest for fuel-efficient cars, companies are refining older technologies while developing new ones. Cleaner-burning diesels and small, more efficient gasoline engines are increasingly used in a range of vehicles, from subcompacts to SUVs. However, the best known and arguably the most popular approach to better gas mileage is the electric-gasoline hybrid.

How Hybrids Work

Hybrids use more than one power source, most commonly a gasoline engine and an electric motor. There are three general types of hybrid. The “parallel hybrid” is the simplest configuration. The engine propels the car, and the motor either provides a power boost to the engine or charges the battery by means of regenerative braking, in which the motor acts as a charging generator. Examples of cars incorporating a parallel hybrid system are the Honda Impulse, Civic and Accord. The “series hybrid” uses only an electric motor as the propulsion source with a gasoline engine to charge the battery and provide electricity for a car’s systems. Examples include vehicles that have been dubbed electric cars, such as the Chevrolet Volt and the Cadillac ELR. In the “series-parallel hybrid” system both an electric motor and a gasoline engine provide power outputs to the transmission. The motor can either supplement the engine’s output or provide battery charging through regenerative braking. Electric-only operation is also feasible. A computer monitors driving conditions and battery state and optimizes the mix of motor and engine output. Examples include all Toyota and Lexus hybrids, as well as the Ford C-Max and Fusion.

Many Toyota and Honda Hybrids

There is a great variety of hybrid car models. Toyota/Lexus and Honda/Acura currently produce the most. Toyota makes the iconic Prius in several versions starting at about $24,000, the original Prius liftback, the smaller Prius c, the station wagon-like Prius V and the Prius plug-in. Hybridized gasoline models include the RAV4, Avalon, Camry and Highlander. Lexus for the most part makes luxury hybrids based on several of the Toyota models and priced accordingly higher, from about $30,000. Honda hybrids start at about $24,000 and include the Civic, Accord, Accord plug-in, Insight and CR-Z. Acura makes the RLX ($48,000 and up) and upcoming NSX, both of which utilize three motors, one on each of the front wheels, the third integrated with the engine as motor-generator. Both Toyota and Honda have indicated that fuel cell technology is a priority for the future. Hybrids are also produced by Hyundai (Sonata), Kia (Optima), Nissan (Altima), Infinity (Q50, M35h, QX60) and Mitsubishi (PX-MiEV plug-in). There are indications that these companies are focusing on EV technology and, in the case of Hyundai and Kia, hydrogen fuel cell technology.

Ford Leads American Manufacturers in Hybrids

Ford’s hybrids start at about $25,000 and include the Fusion Energi, Fusion Energi plug-in, C-Max, C-Max plug-in, Escape and the Lincoln MKZ. General Motors also produces hybrids. Cadillac has the ELR ($76,000), a gasoline-assisted electric car, and the Escalade Hybrid ($73,000). Chevrolet has the well-received Volt and two hybrid trucks, the Silverado pickup and Tahoe SUV. Buick has the LaCrosse eAssist and Regal. Chrysler has no hybrids currently.

German Luxury Hybrids

BMW, Mercedes and Porsche are all producing hybrids and researching advanced technologies. BMW hybrids ($50,000 and up) include the i8 plug-in, X6, and the ActiveHybrid series (3, 5 and 7). A concept car, the Hydrogen 7, is in the works. Mercedes has the E400H ($50,000) and the milestone S400HV ($90,000), which uses lithium ion battery technology. Porsche has the Panamera SE-Hybrid and a plug-in version ($95,000 and up) as well as the Cayenne S ($70,000). Porsche reportedly is aiming to produce hybrids of all models including the 911 and is working on an electric vehicle.

The Future of Hybrids

It is difficult to predict with any precision what the future holds, but there are indications. Series-parallel and parallel hybrids will likely remain as the most popular form of hybrid in the near term, as they are the most common, have achieved wide acceptance, have excellent fuel efficiency and are practical in terms of range. All-electric vehicles and series hybrids are destined to grow as research proceeds and batteries become smaller, less costly and more efficient. Research by innovative car companies on hydrogen fuel cell-driven series hybrids is continuing while addressing the logistics of establishment of hydrogen fueling stations.