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Published Jan/Feb 2006

Left: The Civic’s powertrain teams an electric motor with a tiny three-cylinder gasoline engine.

With improved fuel economy and power,
Hybrids are growing in popularity.
By AAA National

Not surprisingly, public awareness of hybrid automobiles has increased in direct proportion to rising gasoline prices. Most consumers think of a hybrid vehicle as a car or truck that teams a gasoline engine with an electric motor in order to provide better-than-average fuel economy. While that definition is generally true, maximizing miles per gallon is only one advantage to building hybrid cars and trucks. Automakers today use hybrid powertrains to achieve a number of different ends, not all of them tied to fuel economy.

Here is a selection of hybrid cars and trucks available nationwide. They are grouped into categories based on the manner in which the gasoline engine and electric motor work together to power the vehicle. There are some interesting differences between the vehicles and in the manufacturers’ goals in developing them. Be forewarned, not all hybrids are created equal.

Full hybrids

The term “full hybrid” describes a vehicle whose wheels may be driven by the electric motor only, the gasoline engine only, or both working together in tandem. Full hybrids also employ energy-saving features such as an idle stop system to shut down the gasoline engine when the vehicle is not moving, a regenerative braking system to recharge the battery pack during deceleration, and an electronically controlled, continuously variable automatic transmission (CVT) to ensure optimum gearing for any situation. A sophisticated electronic control unit continually monitors and adjusts every part of the powertrain to maintain optimum efficiency.

The Toyota Prius is probably the most recognized hybrid automobile in the world. The first generation model debuted in Japan in 1997 and came to the United States in the summer of 2000. A significantly upgraded second generation Prius was introduced in 2004 and has garnered numerous awards for its innovative design. The Prius uses Toyota’s Hybrid Synergy Drive® powertrain and is designed primarily with fuel savings in mind while providing a mid-size interior with seating for four. It features EPA city/highway fuel economy ratings of 60/51 mpg. (Hybrid vehicles are more fuel efficient in city driving.)

Toyota’s Highlander Hybrid and Lexus RX400h sport utility vehicles feature a somewhat different implementation of Hybrid Synergy Drive. Offered in all-wheel-drive or front-wheel-drive (Highlander only), these models come with a 3.3-liter V-6 gasoline engine that is paired with either one (front-wheel drive) or two (all-wheel drive) electric motors.

While these models do offer fuel savings, the combined power of their engines and motors is somewhat greater than that of their non-hybrid counterparts. The result is very strong performance, but if drivers take too much advantage of the extra power, they will find the fuel economy of these “performance hybrids” is not much better than the standard versions. These vehicles offer EPA city/highway fuel economy ratings of 31/27 (RX400h and Highlander 4WD) and 33/28 (Highlander 2WD).

The Ford Escape Hybrid and Mercury Mariner Hybrid also are two versions of the same basic vehicle. They employ hybrid powertrains based on technology licensed from Toyota, although that company does not directly supply any of the components to Ford. The hybrid Escape and Mariner use a 2.3-liter four-cylinder engine paired with a single electric motor to offer V-6 performance with fuel economy that exceeds that of their nonhybrid four-cylinder models. Ford calls this a “no compromise approach to hybridization,” and it works quite well with EPA fuel economy ratings of 36/31 (2WD) and 33/29 (4WD).

Mild hybrids

The term “mild hybrid” describes a vehicle in which an electric motor supplements the gasoline engine’s power during high-load conditions, but the automobile is never powered by the electric motor alone. Although the gasoline engine is shut down at stops to conserve fuel, it always provides power when the vehicle is moving.

Like full hybrids, these models employ regenerative braking and a continuously variable automatic transmission to help maximize efficiency. However, several of these cars can also be equipped with a manual transmission.

The two-seat Honda Insight was the first hybrid sold in the United States. This diminutive commuter car features Honda’s “Integrated Motor Assist®” (IMA) powertrain, which teams an electric motor with a tiny 1.0-liter, three-cylinder gasoline engine. The Insight offers a choice of a continuously variable automatic transmission or manual transmission, and its fuel efficiency is aided by its extremely light weight (under 2,000 pounds) and the use of virtually every fuel-saving technology available today.

As a result, Insight has repeatedly topped the EPA fuel economy ratings with city/highway scores of 61/66 (manual) and 57/56 (continuously variable automatic). While the Insight may not meet the needs of many car buyers, it does show what is possible when fuel economy gets top priority.

The Honda Civic Hybrid puts the IMA powertrain to use in a more practical four-person package. Along with the buyer’s choice of a continuously variable automatic or manual transmission, the Civic offers a 1.3-liter four-cylinder engine that is still somewhat smaller than the 1.7-liter powerplant in non-hybrid versions of the car. The Civic Hybrid offers increased fuel economy in a highly competent and proven vehicle that differs little from its siblings other than its excellent 48/47 (continuously variable automatic) and 46/51 (manual) EPA city/highway fuel economy ratings.

The Honda Accord Hybrid is the latest vehicle from that manufacturer to employ its IMA powertrain technology. Unlike most other hybrids, the Accord Hybrid is offered only with a conventional five-speed automatic transmission. It also has a relatively large and powerful 3.0-liter V-6 engine that is only marginally smaller than the V-6 available in non-hybrid Accords. Adding an electric motor makes the hybrid the most powerful Accord you can buy, and Honda has positioned this model at the top of the line. Much like the Toyota Highlander Hybrid and Lexus RX400h, the Accord is a “performance hybrid” that offers more of two good things–power and fuel economy. Its EPA city/highway fuel economy estimates are 29/37.

Pseudo hybrids

The term “pseudo hybrid” describes a vehicle that contains many components of a hybrid powertrain but does not use an electric motor to actually propel the vehicle. A pseudo hybrid is powered exclusively by its gasoline engine, which employs an engine idle stop system to achieve a small gain in fuel efficiency.

The Chevrolet Silverado 1500 Hybrid and GMC Sierra Half-ton Hybrid qualify as pseudo hybrids. These trucks have a motor/generator located between the engine and the transmission that provides electrical power to a modestly sized 42-volt battery pack. The motor/generator and batteries do not power the vehicle; instead, they are used to restart the engine when leaving a stop. GM calls this a “flywheel alternator starter” (FAS) hybrid system, and it provides nearly silent and instantaneous engine restarts. It also supports the one to two mpg fuel-economy gain provided by the idle stop system, which results in EPA city/highway fuel economy estimates of 18/21 (2WD) and 17/19 (4WD) for these trucks.

If better starting were all that GM’s motor/generator offered, one might question the need for such an elaborate solution. However, the company took advantage of its first foray into hybrid technology by adapting it to provide another benefit that is uniquely suited to these particular vehicles. The motor/generator on these hybrid trucks also provides 2,400 watts of 120-volt power to four conventional household outlets: two in the cab and two in the truck bed. These outlets allow trades-people to plug in drills, saws and other construction equipment at work sites with no available power. The truck can even be locked with the engine running and the keys removed to provide up to 32 hours of continuous power. To prevent the driver from becoming stranded, the system will automatically shut down the engine before the gas tank is completely empty.

Today’s hybrid cars and trucks are scattered across a broad spectrum of usage categories that include fuel economy, practical transportation, top-of-the-line performance and mobile utility. They all offer improved fuel economy, but the real news is that they go beyond fuel efficiency and use hybrid technology to offer vehicle capabilities that were impossible just a few years ago.



Above: The Ford Escape Hybrid uses a four-cylinder engine paired with an electric motor to offer V-6 performance and up to 36 mpg in the city.

Below: The Honda Civic Hybrid can get 48 miles per gallon in the city.



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