Hybrid Sports Cars

Hybrid Sports Cars

Special to Edmunds.com from Green Car Journal

In the not-too-distant future, that blur in the fast lane is as likely to be motivated by a high-tech hybrid power plant as it is an exotic, high-horsepower internal combustion engine. Surprised? You shouldn't be. Gas-electric hybrid vehicles are beginning to emerge in various forms these days, from Honda's mainstream Civic Hybrid and Toyota's acclaimed Prius to Ford's hybrid Escape SUV. Ultimately, hybrid power plants will become just another option at the showroom.

Some of the recent concepts forwarded at major auto shows share the direction that automakers have in mind. One of these directions speaks to the performance buff in us — high-performance hybrid sports cars. One such glimpse into the future, Mitsubishi's gas-electric hybrid Eclipse Concept-E, provides a formidable example.

The Concept-E's front wheels are driven by a parallel hybrid system integrating an electric motor with a 3.8-liter V6, for a combined 270 horsepower. The automaker's innovative E-Boost system channels an additional 200 hp to the rear wheels from a 150 kW electric motor located behind the cabin, powered by lithium-ion batteries secreted along the center of the vehicle. E-Boost is activated by aggressive throttle to provide an immediate boost in acceleration, much like a conventional turbo- or supercharger, transforming the car into a 470-hp, all-wheel-drive terror that raises the hybrid performance bar to new levels.

A look inside reveals further emphasis on the car's hybrid technology, with a decidedly futuristic twist. Centrally placed is a complex 3-D video imaging display that offers simulated gauges, diagnostic information and interactive displays. The gearshift, looking as much the part of a fighter jet's sidestick controller as a shifter, connects to a six-speed transmission that allows for both manual and automated shifting.

The familiar corporate grille sits atop a gaping air intake and between large headlight assemblies featuring unique plasma lamps. Its teardrop-shaped details — including side glass, door-handle cutouts and roof profile — pay homage to the second-generation Eclipse that was cherished by the street-tuner crowd. But the overall look of this iteration is thoroughly modern and striking. The muscular fender bulges speak of immense power and purpose, not inconsequentially housing wild nine-spoke, 20-inch wheels wrapped by 245/40R20 performance tires up front and 275/35R20 at the rear, suspended by independent multilinks at all four corners. It's a theme well integrated with the car's ground-hugging lower styling and aggressive stance, further supporting Mitsubishi's fusion of the disparate perceptions surrounding high-power, speed and hybrid technology into a single package.

Subaru Steps Out

Then there's Subaru with its B9 SC "Scrambler" hybrid electric concept. This advanced car blends the design direction of Subaru's Andreas Zapatinas — formerly head of design at Alfa Romeo — with a unique hybrid electric drive technology that works seamlessly with Subaru's Symmetrical All-Wheel-Drive systems, and also is adaptable to its current vehicle platforms.

This automaker's Sequential Series Hybrid Electric Vehicle (SSHEV) system places a generator between a gasoline-powered 2.0-liter, horizontally opposed four-cylinder engine and transmission — with a two-way clutch, high-performance electric motor and all-wheel-drive transfer gearing integrated into the transmission case. What's unique about the SSHEV power plant is that its Boxer gasoline engine supplements the electric drive motor, rather than the other way around. Up to about 50 mph, the gasoline engine's primary role is to charge the laminated lithium-ion batteries that power the hybrid vehicle's electric motor. The gasoline Boxer engine takes over as primary propulsion above 50 mph, a speed range that's most efficient for this internal combustion power plant. Both electric and gasoline power plants jointly provide power under demanding driving conditions.

With this high-tech setup, Subaru says it will be able to offer customers the kind of performance now enjoyed with its turbocharged models by using its own hybrid electric drive technology.

Mazda Makes its Mark

The Miata never has left a large physical or environmental footprint, but that hasn't stopped Mazda from projecting an even cleaner future for its little sports car through its Ibuki concept. The Ibuki — its name coined from a Japanese word that means "to invigorate" — integrates a hybrid system that mates a 1.6-liter, four-cylinder engine to an electric motor and a six-speed manual transmission. This hybrid power plant eliminates idle time by shutting the car's internal combustion engine down when stationary, not only saving fuel and reducing emissions but also electrically assisting acceleration once the car needs to get moving again.

The virtues of lightweight materials are seen in both vehicle performance and efficiency, and the Ibuki aims to reap both rewards. The fenders, hood, rear floor panel and door outer panels are all made of lightweight reinforced plastic, while the driveshaft and engine frame are constructed of carbon fiber. The car's 18-inch magnesium alloy wheels house aluminum brake discs. All contribute to a lower weight that works to ensure responsive handling and less load on the engine.

A rigid frame mounts the engine far behind the front axle line for better handling. These underpinnings are wrapped in a rounded body that evokes the first Miata, but with a flat, chiseled upper surface, unframed windshield and unique headlight/taillight treatment that give this sports car concept its own distinct style. Featuring a longer wheelbase than the current Miata but an overall length 12.4 inches shorter, the wheels have been pushed to the extreme outer corners of the car in a stance that reveals its true sporting intentions.

Mazda's Miata reinvented the sports car with its introduction in 1989. This time around, it appears that Mazda may be aiming to do it again, but this time with a decidedly hybrid edge.

Beyond Straight Hybrids

Even as hybrids are storming the show circuit and mounting an assault on new car showrooms, other advanced power plants are being examined for sports cars of the future. Mazda, for instance, recognized some time ago that its rotary engine and clean hydrogen fuel operate quite well together. In fact, this automaker fielded a developmental MX-5 Miata hydrogen rotary sports car in the early 1990s.

Reinforcing Mazda's enduring interest in what many consider the ultimate environmental fuel is its latest developmental vehicle, based on the automaker's acclaimed RX-8. The Mazda RX-8 RE integrates Mazda's Renesis hydrogen rotary engine, a lean-burn power plant based on the automaker's next-generation rotary power plant launched last year.

A rotary engine is especially well suited for burning hydrogen since it uses separate chambers for induction and combustion, overcoming the backfiring issues often faced when using hydrogen in piston engines. In addition, Mazda says the separate induction chamber also provides a safer temperature for the engine's dual hydrogen injectors with their rubber seals, which can be damaged by the higher temperatures of conventional engines. Dual injectors are used in each of the engine's twin rotor housings since hydrogen has an extremely low density, thus greater volumes of this fuel must be injected than gasoline.

Mazda's RX-8 RE aims to provide a traditional driving experience as it achieves extremely low emissions with hydrogen. This is accomplished by integrating a dual-fuel approach that allows seamlessly operating on hydrogen as available, or gasoline when it's not. This is important and reflects Mazda's belief that a dual-fuel system promotes the use of hydrogen and a developing hydrogen refueling infrastructure. The RX-8 RE uses both a conventional gas tank and a high-pressure hydrogen tank.

The Renesis hydrogen engine features 210 hp when running on gasoline and 110 hp on less energy-dense gaseous hydrogen. Power is transferred to pavement through a five-speed manual transmission. Performance is enhanced with 225/45R18 tires over 18x8JJ alloys and double-wishbone multilink suspension front and rear, with stopping power supplied by four-wheel ventilated disc brakes.

An array of advanced technologies is used in the RX-8 RE to allow Mazda engineers to explore their value for a future production hydrogen vehicle. These include an electric motor to boost engine torque at low rpm and an electric motor-assisted turbocharger, both used to improve acceleration at low rpm. An idle-stop system turns off the engine when the car is stopped and then starts again automatically when the driver is ready to accelerate. Regenerative braking recovers energy during deceleration and braking to charge the car's 144-volt battery. In effect, Mazda's RX-8 RE is really a hydrogen hybrid electric vehicle, perhaps the best of all worlds.

As these concepts and prototypes show, hybrid sports cars hold huge potential for the new car showrooms of the future. It's not a question of whether they make their way to American highways, but rather, how soon.

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