Super Technology

Hybrid electric vehicles employ highly advanced technology that would've seemed far-fetched even just 10 years ago. But what's truly impressive is that, despite the newfangled components, hybrids drive and handle just like any other conventionally powered passenger vehicle.

One such advanced feature that all gasoline/electric hybrids currently on the market have is the ability to automatically shut their internal combustion engine off while stopped or coasting under certain conditions to save fuel and cut exhaust emissions. To put the value of this single feature into perspective, consider that the Texas Transportation Institute's 2005 Urban Mobility Study found that an estimated 2.3 billion gallons of fuel were wasted by engines idling in traffic jams in 2003.

The 2006 Honda Civic Hybrid's ability to cruise at highway speeds on electric power alone is an example of how advanced hybrids have become.

Depending on model and circumstances, a vehicle will accelerate on electric- or internal-combustion power when starting up again. Through a system called regenerative braking, hybrids also generate their own electric power while decelerating or braking, with electric drive motors reverting to generators that feed electricity back to the batteries. An alternator charges a hybrid's batteries during normal operation if the battery pack's charge is low.

GM's mild-hybrid system is a much simpler design with a start/stop system that shuts off a Chevrolet Silverado Hybrid or GMC Sierra Hybrid's engine during coast-down at low speeds or when stopped. Three lead-acid batteries help power this 42-volt system, while an integrated flywheel-alternator-starter quickly fires up the engine to provide acceleration from a stop. Like the full hybrids, this mild-hybrid system uses regenerative braking to help replenish the batteries.

Other technologies can be incorporated in hybrid powerplants to increase efficiencies. One example is Honda's Variable Cylinder Management, which is standard on models like the 2006 Accord Hybrid, 2006 Civic Hybrid, and two-wheel drive 2006 Pilot, and optional on the 2006 Odyssey. During low-load conditions, VCM turns a V6 into a fuel-sipping three-cylinder by shutting down one bank of cylinders. The engine changes over from six to three and back to six cylinders seamlessly without a driver ever knowing.

As testament to the seamless integration of electric and gasoline powerplants in hybrid vehicles like Toyota's Prius, if it weren't for this car's control-panel display, most drivers would have a hard time telling where the power is coming from.

Another example of ingenious technology that increases hybrid vehicles' efficiency is electrically assisted steering and braking systems. They're lighter and don't tax the combustion engine, thus reducing fuel consumption. They also allow a hybrid vehicle to drive normally when the engine is shut down during coasting: Traditional hydraulic steering and braking systems stop working as soon as the gasoline engine shuts down. Extensive use of lightweight materials such as aluminum, magnesium, and plastic, one of the hallmarks of the Honda Insight, can also increase a hybrid's overall efficiency.

Initially, hybrid powerplants combined the high-torque characteristics of an electric motor with a smaller-than-normal internal combustion engine to provide adequate power and super-high fuel economy. This example is taken to an extreme with the Honda Insight's 1.0-liter three-cylinder engine and small electric motor, a combination that can achieve fuel economy in the high 60 mpg range.

The market is now shifting toward hybrid vehicles that focus as much on performance as efficiency. The Honda Accord Hybrid and Lexus RX 400h retain the potent V6 engines of their non-hybrid counterparts and add an electric motor for increased performance and efficiency. Some hybrid purists claim this co-opts the intent of hybrid technology by using advanced components to produce greater power and better, but not great, fuel economy. However, a more realistic assessment is that those interested in higher performance get the best of both worlds with a vehicle offering high levels of performance, while also enabling substantially better fuel economy and lower emissions.