SHIRAKAWA, Japan – Toyota Motor Corp. was able to slash its hybrid system costs an estimated 30% on the all-new ‘10 Prius, says chief engineer Akihiko Otsuka.

The auto maker had targeted another 50% reduction, equal to the gains made when it went from the first- to second-generation powertrain, but officials said in January continued high battery costs kept the auto maker from reaching that goal.

Although Otsuka won’t confirm a specific dollar amount, the new system, based on an earlier interview with a senior Toyota research executive, comes in at about $1,750-$2,000, down from roughly $2,500-$3,000 for the ʼ04 model.

At a recent media briefing at the auto maker’s Mobilitas safety center in Gifu prefecture, Otsuka says size, weight and cost reductions ranged from 20% to 35% depending on the component.

For instance, Toyota succeeded in reducing size and weight of the starter-motor by incorporating a reduction gear into the unit.

Otsuka estimates 90% of hybrid system parts are new. The main carry-over component is the car’s nickel-metal-hydride battery pack, which, like the previous model, is supplied by Panasonic EV Energy Co. Ltd., a Toyota subsidiary.

Unlike the previous unit, the new battery is slightly smaller due to packaging improvements centering on the unit’s cooling ducts. Weight remains unchanged, however. The supplier boosted output marginally from 25 kW to 27 kW.

Toyota will introduce a plug-in version of the Prius by year’s end that will employ a lithium-ion battery. In the U.S., the auto maker plans to lease 150 units.

“The determining factor for choosing the battery is the car’s concept,” Otsuka says. “For plug-in hybrids, lithium is better.”

Still, the Toyota engineer believes NiMH is more reliable – thus, the decision not to switch to Li-ion for the new standard Prius.

That could change in the future, however. Panasonic Corp., formerly Matsushita Electric Industrial Co. Ltd. and minority shareholder in Panasonic EV Energy, is finalizing its acquisition of Sanyo Electric Co. Ltd., Japan’s leading maker of small Li-ion batteries.

The takeover, which reportedly will cost Panasonic ¥800 billion ($8.1 billion), now is scheduled for summer, according to Japanese news reports. When it happens, Toyota could have more direct access to another supplier’s technology. At present, the auto maker is developing a Li-ion battery technology in-house.

  • An upgraded regenerative braking system that boosts brake-energy savings an estimated 10%. A Toyota spokesman in the U.S. says regenerative braking accounts for 30% of the car’s fuel efficiency.
  • An 18% energy savings when running the car’s air-conditioner through the adoption of a new 2-stage evaporator-with-injector system.
  • Unspecified savings from a new exhaust-heat recovery system that shortens engine warm-up time and a cooled exhaust-gas recirculation system that reduces piston pumping losses by lowering intake-manifold pressure to near-atmospheric pressure levels.

Meanwhile, Otsuka says Toyota has no plans to make a full electric vehicle similar to the Li-ion-powered Mitsubishi Motors Corp.’s i-MiEV that is scheduled to go on sale in July.

Other hybrid system improvements that contributed to the Prius’ industry-leading 50-mpg (4.7-L/100 km) rating:

Also contributing to better mileage – up 4 mpg (1.6 km/L) over the current model – is the new Prius’ 1.8L 2ZR gasoline engine. Modified to eliminate use of friction-causing accessory belts for the Prius application, the 4-cyl. 2ZR currently is featured on the Corolla, Aurus, Scion xD, Matrix and Pontiac Vibe.

The engine produces 98 hp and 105 lb.-ft. (142 Nm) of torque, both up nearly 30% over the current Prius’ 1.5L. The higher torque enables the new Prius to run at lower rpm on the highway, consuming less fuel.

Combined horsepower of the gasoline engine and electric motor was boosted 21% to 134 hp.

The chief engineer notes the 2ZR Atkinson Cycle engine, like other Toyota gasoline powerplants, can run on E10, a fuel mixture comprising 90% gasoline and 10% ethanol.

Honda Motor Co. Ltd.’s new Insight, which Otsuka characterizes as a mild hybrid, achieves 41 mpg (5.7 L/100 km) in combined city-highway driving, 9 mpg (3.6 km/L) less than the new Prius.

Otsuka says Toyota has no plans to shift away from full hybrids. At present the auto maker has only one mild hybrid in its lineup, the Estima Hybrid minivan sold in Japan.

Otsuka says his team – numbering 3,000 over the term of the project – took 4.5 years to develop the new Prius from concept to production. As the model is based on the Corolla/Aurus/Matrix platform, it has virtually no carry-over components from the current Prius.

Also on tap is a new lower-cost hybrid base on the Yaris and designed to compete head to head with the Insight, though Toyota has not released any technical details or timing. Media reports suggest a market launch in 2011.

As with the ʼ04 Prius, the ʼ10 model will be produced at Toyota’s Tsutsumi plant and Toyota Auto Body Co.’s Fujimatsu facility in Aichi prefecture.

Although the auto maker has not disclosed a global sales target for the car, management expects U.S. deliveries to reach 180,000 units in 2010. Last year, Toyota sold 285,675 units globally, including 158,884 in the U.S.

In Europe, Otsuka believes hybrids have the potential to make inroads as the cost of oxide-of-nitrogen and hydrocarbon filtration equipment for diesel engines increases to meet future Euro 6 emissions standards. Even today, he says, the new Prius achieves better mileage than Volkswagen AG’s small diesel. In the Jetta, the 2.0L diesel achieves 29/40 mpg city/highway (8.1-5.9 L/100 km) in the U.S.

Looking at suppliers, Otsuka confirms the electric motor and inverter for the Prius are produced at Toyota’s Honsha and Hirose plants in Aichi prefecture. The car’s heating, ventilating and air-conditioning system is supplied by Denso Corp., with the electric compressor coming from Toyota Industries Corp.

Denso also supplies the car’s body, engine and inverter electronic-control units.

The vehicle’s electronically controlled steering system, featuring a new motor-powered assist device on the column, is produced by JTEKT Corp., while the car’s braking system is manufactured by Toyota at an unspecified plant. The steering system motor is a brushless type that reduces friction and increases power.

Yazaki Corp. supplies the special instrument cluster that incorporates an energy-flow meter, eco meter, new touch tracer system and various other indicators that in theory help the driver boost fuel economy.

Despite reducing hybrid system weight by about 66 lbs. (30 kg), the overall vehicle weight increased by 110 lbs. (50 kg) due to the adoption of new safety systems and reinforcements needed to achieve Japan’s highest crash-test rating.

The new 3,042-lb. (1,383-kg) Prius achieved a 6-star crashworthiness rating under the Japan New Car Assessment Program. It has seven standard airbags, including driver and front passenger, front and rear side curtain, driver and passenger seat-mounted side-impact and driver’s knee airbags.