TOKYO – Plug-in hybrid electric-vehicle technology is the “most realistic medium-term” option for auto makers from a cost and performance standpoint, says Shigeki Suzuki, a senior managing officer at Toyota, speaking at a recent conference here.

Toyota’s plug-in Prius earns 90.5 mpg (2.6 L/100 km) under Japan’s JC08 test cycle, 80% higher than the conventional Prius hybrid, he says, noting 15% of Prius PHEV owners have achieved better than 235 mpg (1.0 L/100 km). In 2012, Toyota sold 27,280 Prius PHEVs out of its total hybrid sales of 1.2 million units.

Takeshi Miyamoto, an engineering director with Nissan’s EV technology-development division, says recent upgrades to the Leaf all-electric car have contributed to a 14% increase in driving range.

The Leaf now can cover 142.5 miles (228 km) on a single charge under Japan’s JC08 test cycle, compared with 125 miles (200 km) when it was launched in December 2010, he says.

Following Toyota’s first-generation Prius strategy of bringing technical improvements to market as soon as they are ready, Nissan cut 175 lbs. (80 kg) from the first-generation model that weighed 3,345 lbs. (1,520 kg). This was achieved by redesigning the Leaf’s electric powertrain and modifying the battery’s structure.

Miyamoto says the Leaf’s new electric powertrain joins the inverter, motor, power delivery module and reduction gear into a single unit, reducing the size and weight 30% and 10%, respectively. Output remains unchanged at 80 kW (107 hp).

The Leaf’s lithium-ion battery retains its basic structure comprising 48 modules, each with four 1.9V cells for a total of 192 cells. However, components have been lightened and modules and case structure streamlined, contributing to a weight reduction of 44 lb. (20 kg). Total voltage and energy are 360 volts and 24 kWh, unchanged.

At last year’s Battery Expo in Japan, a senior Nissan research executive told WardsAuto the Li-ion battery pack for the Leaf would come down to ¥50/watt-hour ($0.52/watt-hour) in fiscal 2013.

Other new Leaf features include a heat-pump cabin heater that substantially reduces energy consumption when the heater is engaged. Nissan declines to provide details about energy savings. However, a supplier source claims the new system, which replaces the previous model’s electric heater, cuts energy consumption in half.

Additionally, the new Leaf’s regenerative braking system works at speeds as low as 1.9-4.4 mph (3-7 km/h).

Nissan also has slashed the amount of the rare-earth element dysprosium in the Leaf’s electric motor magnets 40%. Dysprosium is added to neodymium-based magnets to increase heat resistance, the auto maker says.

In the microhybrid segment, mainly comprising stop/start systems, Mazda says its new ‘i-ELOOP’ device featured on the Mazda6 contributes up to 10% fuel savings when used with the auto maker’s “idle/start” system.

Tatsuro Takahashi, a staff manager with Mazda’s vehicle systems development group, says the device, which employs a capacitor to store regenerative braking electricity, powers air-conditioning and other electrical systems including headlights, power steering, wipers, power windows and navigation/audio. Nippon Chemi-Con supplies the double-layer capacitor.

The system eventually will be adopted for B-through-C/D segment cars, which range from the Mazda2 up through the CX-5 cross/utility vehicle and Mazda6 sedan. “The advantage of the system,” according to Takahashi, “is instantaneous recharging.”