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TOKYO – Japanese auto makers provided a clearer roadmap to their alternative powertrain future at this year’s Tokyo Motor Show, with game plans ranging from hydrogen-fueled internal combustion engines to full electric vehicles.

Mazda Motor Corp. generated some of the biggest buzz with the announcement it would begin marketing its Premacy Hydrogen RE Hybrid in early 2009.

The hybrid vehicle offers 40% more power than the experimental hydrogen/gasoline-powered RX-8 Hydrogen RE, which was launched in March 2006 and to date has been leased to eight research institutes and local governments in Japan. Beginning next summer, the auto maker will provide another 30 units to HyNor, a Norwegian project promoting hydrogen transportation.

The Premacy Hybrid, which debuted at the 2005 Tokyo show, is a series hybrid, meaning unlike parallel hybrids such as the Toyota Prius, the internal combustion engine isn’t used to directly drive the wheels.

Main powertrain components include a hydrogen rotary engine (a modified RENESIS rotary with 1.3L displacement), generator, inverter, electric motor and 346-volt lithium-ion battery pack. Power generated by the motor, whether in hydrogen or gasoline mode, runs through the generator to recharge the batteries or drive the electric motor.

Akihiro Kashiwage, program manager of both Mazda models, says power for the Premacy Hybrid was boosted to 147 hp (from 107 hp for the RX-8 Hydrogen), while driving range in hydrogen mode was doubled to 125 miles (201 km).

Kashiwage attributes much of the increased driving range to the Premacy Hybrid’s larger high-pressure hydrogen fuel tank, which can hold 40 gallons (150 L) at 5,075 psi (350 bar). The RX-8 Hydrogen’s tank can carry 29 gallons (110 L).

The layout of the Premacy Hybrid’s hydrogen rotary engine has been changed from longitudinal to transverse, while intake and exhaust resistance and combustion efficiency have been improved to yield higher output across a wide range of engine speeds.

Mazda is targeting a doubling or even tripling of leases with the new Premacy Hybrid, from that of the RX-8 Hydrogen. However, Kashiwage says the volume will be constrained by the limited number of hydrogen fueling stations in Japan – now totaling 11.

“For sales to grow, there needs to be a fueling infrastructure,” he says.

Kashiwage declines to reveal the cost of the hybrid system other than to say it is expensive. But he says the powertrain is considerably cheaper than current platinum-dependent fuel cells under development and undergoing fleet testing.

Meanwhile, Toyota Motor Corp. shows some of the hand it expects to play when it comes to fuel cells. Its next FCHV (fuel-cell hybrid vehicle) features four high-pressure 10,150 psi (700 bar) hydrogen fuel tanks, double the pressure level and storage capacity of the current generation.

In late September, the auto maker conducted a long-distance road test with a pair of fuel cell-powered Kluger SUVs (the base model used for the FCHV) between Osaka and Tokyo. The vehicles covered the 350-mile (563-km) distance without refueling and with their air conditioners in full operation. Estimating from the amount of hydrogen left in the tanks, Toyota reported a driving range of 490-550 miles (780-880 km), 25% above the current-generation FCHV.

Hidemi Onaka, project general manager, credits use of the high-pressure fuel tanks for increasing the FCHV’s range. In addition, he says all key components have been improved with the exception of the power control unit. Although volunteering few details, he confirms the fuel cell’s stack is smaller, while output was raised to 121 hp, from 107 hp. Torque is unchanged at 192 lb.-ft. (260 Nm) and, like its predecessor, the vehicle can achieve speeds of nearly 100 mph (161 km/h).

Onaka doesn’t reveal the launch date for the new model but hints at the latter half of 2008. To date, Toyota has leased 18 FCHVs, including seven in the U.S.

The Toyota official expects to complete technical development of the model by about 2012, roughly the same timeframe set by Honda Motor Co. Ltd. for its FCX Clarity that bowed at the Los Angeles auto show. He says stack size still must be cut in half before the FCHV will be ready for more mainstream marketing.

Of key components, the fuel cell, high-pressure tank and motor are produced by Toyota. The battery is supplied by Toyota subsidiary Panasonic EV Energy Co. Ltd. and is the same as the one used in the Prius. Other components were developed with suppliers such as Denso Corp., though Onaka declines to specify sourcing.

Nissan Motor Co. Ltd., Mitsubishi Motors Corp. and Fuji Heavy Industries Ltd. all focused on mini-EVs powered by Li-ion batteries at the Tokyo show.

Nissan’s Pivo2, a futuristic mini-EV with a 360-degree rotating cabin, runs off a pair of Li-ion battery packs that provide enough punch to cover 80 miles (129 km) per charge while reaching speeds of 75 mph (121 km/h).

The tiny 3-seater can be driven directly into parallel parking spaces, rather than having to be backed in, thanks to individual motors that allow each of the wheels to rotate up to 90 degrees. Chief designer Masato Inoue says the car is part of Nissan’s long-term product plan.

Inoue puts the cost of the Pivo2’s laminated Li-ion battery pack at nearly double that of the rest of the vehicle. Still, he is optimistic cost will come down early in the next decade, aided by the auto maker’s collaboration with NEC Corp.

In April, Nissan, NEC and NEC subsidiary, NEC Tokin Corp., formed a joint venture to develop and produce Li-ion batteries for hybrid and electric vehicles. Production is scheduled to start in 2009.

Nissan won’t reveal the battery’s power density, but an engineer says it is more than 3.5 kW/kg, the level realized in the original Pivo concept unveiled in 2005 and the X-Trail fuel-cell vehicle. In work conducted in its research laboratories, Nissan claims to have achieved 8 kW/kg.

At Mitsubishi, the majority of emphasis is being placed on mini-EVs and Li-ion batteries, if the auto maker’s Tokyo exhibit is any indicator.

The auto maker’s i-MiEV Sport, which debuted at the Frankfurt Auto Show in September, also was a headliner in Tokyo. The battery-powered car, based on Mitsubishi’s popular 0.66L mini “i” model, remains two years from market launch.

Among its features are an electronic 4-wheel-drive system, electronic yaw-rate control and Mitsubishi’s new all-wheel-control system (S-AWC) that integrates antilock brakes and vehicle stability controls to regulate traction and braking at all four wheels.

Kenichiro Wada, a research official in Mitsubishi’s development engineering office, says batteries are the best powertrains in terms of well-to-wheel efficiency and boast the lowest carbon-dioxide emission levels.

In Japan’s 10-15 city-driving test cycle, electric vehicles score 28.5% in efficiency, Wada says. “This is more than double gasoline vehicles, at 13%, and 4%-5% more than gas-electric hybrids.”

Wada adds that the i-MiEV is responsible for 72% less CO2 than the gasoline version of the 0.66L car and approximately 50% less than a comparably sized hybrid. “For every 10,000 km (6,250 miles), one metric ton (1.1 tons) of CO2 is reduced,” he says.

Powered by a Li-ion battery and 63-hp permanent magnet motor, the model has a driving range of 100 miles. Wada’s team at Mitsubishi’s research and development center in Okazaki eventually hopes to boost range to 125 miles, though no timetable is given.

The i-MiEV, which produces 133 lb.-ft. (180 Nm) of torque, can reach speeds of 112 mph (180 km/h). In fact, quick acceleration is one of the car’s outstanding features. It needs just 20.1 seconds to cover a quarter mile (0.4 km) from a standing start, nearly a second faster than the turbocharged version of the i.

And it is quiet, says Wada, who estimates the car is five decibels quieter than the gasoline i when accelerating to 37 mph (50 km/h).

With the unveiling of the i-MiEV Sport in Frankfurt, Mitsubishi formally switched battery suppliers and now is working exclusively with Kyoto-based GS Yuasa Corp.

In May, the auto maker entered into a joint venture with the supplier and Mitsubishi Corp. (Mitsubishi’s trading-house affiliate) to develop and produce large-capacity/high-performance Li-ion batteries.

The companies are targeting 2009 as the production startup on a new ¥3 billion ($260 million) automated line inside GS Yuasa’s Kyoto plant.

The i-MiEV Sport’s battery pack, placed under the floor where the i’s fuel tank is situated, consists of 22 four-cell modules combining for 330 volts and 16 kW/h. Meanwhile, the inverter, battery charger and motor all are squeezed under the rear seat where the gasoline model’s engine and transmission are located.

As a result of this layout, there is no loss of cabin space and the car can be assembled on the same line with the standard i, as all other body components are the same.

Other high-tech features include an aluminum spaceframe; blue light-emitting diodes for interior lighting and rear-combination lamps; and heat-absorbing glass.

Mitsubishi President Osamu Masuko says the auto maker now plans to launch the i-MiEV in 2009, a year ahead of schedule.

In an interview prior to the Tokyo show, Wada reveals Mitsubishi plans to sell 1,000 units in the first year, with sales increasing to 3,000-4,000 by 2014, at which time he predicts the total EV market in Japan will reach 5,000 units.

“Unless,” he qualifies, “a large producer like Toyota or Honda decides to promote the concept. Then demand could be larger.”

Last autumn, the auto maker began a series of fleet tests involving 40 vehicles and five electric utilities in Japan, including the two largest, Tokyo Electric Power Co. Ltd. and Kansai Electric Power Co. Ltd.

Fuji, maker of Subaru cars, displays its latest R1e, an EV version of its 0.66L R1 minicar. Powered by a 346-volt Li-ion battery, researchers say the 2,020-lb. (916-kg) car can run 50 miles (80 km) on a single charge. With a high-power quick charger, its battery can reach 80% of capacity in just 15 minutes.

Fuji, in conjunction with Tokyo Electric, currently is conducting a fleet test involving 40 R1es.

Fuji also displays a battery-powered hatchback, the G4e, which it claims can run 125 miles on a single charge. The concept car features a 346-volt Li-ion battery pack and 87-hp motor with inverter.