Concept Cars of a Different Color …Green

April 10, 2008
Not all of the latest concepts are packing lithium-ion, but there’s a definite drive toward more environmentally benign vehicles.

Patrick G Mahoney
Associate editor

Some years it ’s all about style. Other years it’s performance or electronic wizardry. But this year, escalating energy costs and concerns about global warming have designers scrambling for the best technology or combination of technologies to wring the last drop of energy from their futuristic concepts. Here’s a look at some of the contenders for the green throne.

Jeep Renegade
The Renegade looks like a lunar golf cart. But the marketing guys describe this two-passenger concept as a “Bluetec diesel range-extended electric vehicle in an open-air, sustainable design package.”

Propulsion starts with a 40-mile lithium-ion battery pack. A range extender (small-displacement 1.5-liter, three-cylinder Bluetec Diesel engine) boosts the range to about 400 miles. The Diesel generates an extra 115 horses when needed and reduces exhaust emissions compared to standard gas engines. Renegade boasts equivalent petroleum fuel economy of 110 mpg. Lightweight aluminum architecture and regenerative braking improve efficiency, and dual electric 200-kW (268-hp) motors handle 4x4 duties.

Cadillac Provoq

Cadillac’s hydrogen-fuel-cell crossover combines a fifth-generation fuel-cell system and a lithium-ion battery. The fuel-cell technology produces more power than the preceding generation despite being only half the size. Provoq can cover 300 miles on a single fill-up of hydrogen: 280 miles from hydrogen and 20 miles on battery electric energy.

Two 10,000-psi (700-bar) composite storage tanks under the rear cargo floor hold 13.2 lb of hydrogen that feed the fuel-cell stack under the hood. Hydrogen mixes with oxygen to generate electricity, up to 88 kW of continuous power. The lithium-ion battery pack stores up to 9 kW-hr of electrical energy and provides a peak 60 kW for additional performance.

Electricity from the fuel cell is distributed to a 70-kW coaxial drive system for the front wheels and individual, 40-kW wheelhub motors on the rear wheels for all-wheeldrive capability.

Dodge ZEO
“The ZEO is designed for people who are used to being surrounded with information and virtual friends at all times,” says Lou Gasevski, principal interior designer. ZEO stands for Zero Emissions Operation. Dodge’s latest concept is a four-passenger, all-electric, 2+2 sport wagon. With 23-in. wheels on the corners, plenty of guts, and a sassy, low profile, ZEO is a treehugging techie’s muscle car.

The propulsion system is electric only, with a 64 kW-hr lithiumion battery pack and a 250-mile range. The rear-wheel-drive’s 200-kW (268 hp) single-electric motor chases the ZEO from 0 to 60 mph in under 6 sec, rivaling Chrysler’s HEMI powerplant.

Lexus LF-A Roadster

One of the few concepts with no overt green credentials was this high-performance roadster based on the carbon-fiber and aluminum body of the LF-A coupe. The nearly 5.0-liter V10 engine pumps out more than 500 hp and speeds greater than 200 mph. The engine sits in front of the passenger compartment but behind the front-axle centerline, a so-called “front-mid” configuration. It’s connected via a torque tube and propeller shaft to a transaxle controlled by paddle shifters. The torque tube adds rigidity to the drivetrain and chassis while it reduces vibration.

Land Rover LRX 4x4
The 2.0-liter turbodiesel hybrid can run on biodiesel. Land Rover says this powertrain, combined with other technologies, could lower emissions and reduce fuel consumption by as much as 30% compared with other 4x4s of comparable size.

Electric Rear Axle Drive (ERAD) lets the LRX use electric drive alone at lower speeds while retaining 4x4 ability. Offroad, ERAD provides additional torque only when needed. On the road, ERAD lets LRX creep up to 20 mph on electric power before the engine restarts. The electric drive continues to assist the mechanical drive until the engine runs in its most efficient range. The engine stops automatically when the vehicle halts.

The electrical-drive system uses power stored in a high-voltage, high-capacity, lithium-ion battery pack, independent of the normal 12-V battery. This is charged by a regenerative braking system, also working through the ERAD.

LRX incorporates Hill Descent Control and Land Rover’s Terrain Response, basically a sophisticated version of traction control. There are five modes, including the “Eco” mode. Principally for on-road use, this mode configures all the elements of the car’s system for best fuel economy. The other Terrain Response modes are sports, general driving, sand, and ‘grass/gravel/snow’ (for slippery surfaces).

Chrysler ecoVoyager
ecoVoyager’s lithium-ion battery pack supplies primary power for commutes of less than 40 miles. The electric motor, which develops 200 kW (268 hp), lets this concept jump from 0 to 60 mph in under 8 sec. Regenerative braking captures energy and returns it to the battery.

For occasional long trips, a small, advanced hydrogen fuel cell extends the range to more than 300 miles. The propulsion system, which is below the floor, makes more room for passengers and cargo.

Hummer HX
Even the Hummer concept boasts green credentials of a sort — it will burn E85. The HX is a two-door, off-roader with a convertible body. Its FlexFuel 3.6-liter V6 mates to a sixspeed automatic. The open-air experience comes courtesy of a pair of removable roof panels above the driver and front passenger, and a removable rear-roof assembly.

The HX can be configured as an SUT (with the roof assembly removed), a slantback, or a traditional, wagonlike design with a bit more cargo space. Removable doors and removable fender flares should appeal to off-roaders. HID headlamps with focusing rings adjust automatically when they’re turned on — like the lens of an auto-focus SLR-type camera. Front turn-signal lamps and taillamps use LED technology.

The instrument panel has an exposed, extruded aluminum cross-vehicle beam as its foundation and sports a removable cover for storage. The concept’s four seats mount on exposed, aircraft-style tracks.

There is no conventional radio in the HX, only speakers. Passengers plug in an iPod, or similar device, to a USB connector. A reconfigurable gage layout uses LCD screens. The center gage pod, which houses a speedometer and tachometer, changes to a wheelangle indicator when the transmission is in low to give the off-roader more pertinent information. The view of a camera mounted in the rearview mirror displays on the instrument panel.

Like all Hummer production models, the HX has body-on-frame construction with front and rear independent suspensions. The front suspension features an electronic disconnecting stabilizer bar for off-roading. The heavy-duty shocks with piggyback reservoirs are custom made, one at each wheel.

Full-time 4WD transfers torque to the front and rear axles, each of which has a locking differential. Torque meets the trail via custom 35-in. off-road tires on bead-lock-style wheels.

A complete armor kit protects the underbody, and there’s a power winch in the front bumper. The four-wheel-discs are about the only thing that’ll keep this baby from humming.

Mazda Furai

Despite having a 450-hp, three-rotor rotary engine, the Furai burns ethanol and ethanol-gas blends. Furai means “sound of wind.” But if this dark concept has a sound, it’s Batman’s Theme: The Dark Knight would feel right at home cruising Gotham in one of these.

This 180-mph rolling laboratory started with a Courage C65 chassis proven in LMP-2 endurance racing. The company has no plans to race, build, or sell the Furai in the near future (Sorry, Bruce Wayne.)

Furai stands less than 40-in. high but it’s nearly 80-in. wide. The Courage’s carbon-composite tub is essentially intact under the Furai body, including the right-side driver’s seat. An electronic display screen and shift paddles are built into the steering wheel. Doors with butterfly hinges open to the cockpit. The wheels are 14-spoke centerlock aluminum. (Mazda has not released vehicle specifications.)

Mazda Taiki
Mazda says Taiki’s next-generation Rotary Engine 16X or “Renesis,” a 1,600-cc (800 × 2) powerplant with a new trochoid chamber shape, boosts thermal efficiency and torque. These and other innovations help make it a fuel miser. The shape change increases displacement. Still, Mazda says the new engine is as compact and lightweight as the current Renesis.

Lengthening the trochoid radius and eccentricity while making the rotor housing narrower brought a longer stroke, thus shrinking the combustion-chamber aspect ratio. And the surface area-to-volume ratio of the combustion chamber dropped, limiting losses from cooling. The smaller combustion chamber, the company says, promotes flame growth for faster combustion and better fuel economy.

This is the first gasoline rotary engine developed to use direct-fuel injection. The system inherits the basic design of the hydrogen rotary engine, injecting gasoline in a high-pressure spray during the intake cycle, promoting atomization and vaporization of fuel and formation of a stable air-fuel mixture. The latent heat of fuel vaporization lowers the temperature of the air-fuel mixture, thus raising the engine’s charging efficiency. At the same time, it reduces fuel adhesion to the chamber wall — a problem for conventional port-injection systems — while promoting a more homogenous air-fuel mixture. This, in turn, improves thermal efficiency and boosts torque.

Saturn Flexstreme

The Saturn Flexstreme E-Flex uses an electric motor powered by a lithium-ion battery for up to 34 miles of all-electric, emissions-free range. The onboard engine extends driving range to a total of 444 miles. GM has begun production engineering for E-Flex, but production timing depends on continued advancement of key technologies, specifically, the development of lithium-ion batteries for hybrid and electric vehicles. While the featured fuel in the Flexstreme concept is diesel, E-Flex has previously been shown in gasoline and hydrogen-fuel-cell concepts. (Saturn has not released specifications for Flexstreme.)

Mitsubishi RA
The RA offers a twist on the sport coupe with its transversely mounted clean-diesel engine visible through a transparent hood. An aluminum space frame and exterior panels made of lightweight plastic resin reduce weight.

The 2.2-liter, four-cylinder DOHC 16-valve turbo-diesel incorporates valve-lift control with low and high-speed cam profiles actuating the intake valves. A piezoelectric injector, common-rail direct-fuel injection allows for a low static-compression ratio. The turbocharger’s internal vanes control airflow over the turbine and compressor surfaces for optimal boost. The low-emissions diesel delivers a maximum of 201 hp and maximum torque of 310 lb-ft. To clean up tailpipe emissions, the catalytic converter combines a diesel oxidation catalyst, NOx trap catalyst, and diesel particulate filter.

Toyota A-bat
This four-passenger pickup with Hybrid Synergy Drive (HSD) rides on a unibody platform. HSD is the same drivetrain used in the Toyota Prius. NATO’s all-terrain military truck inspired A-BAT’s designers to keep occupants as far forward as possible to maximize rear-bed capacity. A translucent roof panel slides open for tall cargo in the cab. And for even more storage, a large sliding drawer beneath the bed is accessible without opening the tailgate. Inside, translucent solar panels on top of the instrument panel convert sunlight into energy.

BMW says the fuel consumption and emission ratings of its X6 ActiveHybrid Sports Coupé are up to 20% better than comparable cars with conventional drivetrains. ActiveHybrid has two operating modes, one for off-the-line and low speeds, the other for higher speeds. A two-mode transmission delivers variable power via planetary gearsets. And the transmission’s electric drive lets the vehicle operate at fixed transmission ratios within one system, combining the dynamics of a combustion engine and efficiency of electric drive.

The X6 body is a cross between a BMW Coup and a BMW X. The flowing roofline, short front overhang, long wheelbase, and long rear overhang contribute to the coupe silhouette. The front view and rear lights accent the vehicle’s width, typical of an X car, and the extra-large kidney-shaped grille serves as air intake. Front and rear underfloor protection panels are brushed aluminium, and a rear panel hides the tailpipes while driving on electric power only.

Check this out!

To see video of the concept cars from the NAIAS, visit: (Toyota A-BAT) (Mazda Furai) (Ferrari 599 GTB Fiorano) (Audi R8 V12 TDI) (Jeep Renegade) (Mercedes Two-Mode Hybrid) (BMW clean diesel and Dodge Viper)

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