The driving force behind this year's Tokyo Motor Show: powertrains. Japanese automakers unveiled a host of new direct-injection engines, some with advanced variable valve-timing systems, at the biennial exhibition that opened in late October. And many of the concept cars had a drivetrain focus, with several gasoline/electric hybrids and fuel cell-powered models showcased for the first time.

Toyota Motor Corp. got the jump on the competition by unveiling its Prius hybrid-powered 4-door sedan to the media a week before the Tokyo show. Sales of the $17,700 Prius are targeted at 1,000 per month. A decision on whether to sell the car in the U.S. will come in about six months, the company promises.

The 5-seat Prius features a 1.5L gasoline engine and secondary electric motor to drive the front wheels. The gas engine also acts as a generator to recharge batteries during deceleration or braking. It is turned off automatically when the car is stopped, while the electric motor is used to propel the car from a standing start. Once the car reaches higher speeds, the 4-cyl. takes over.

Toyota says the gasoline engine is designed to run at no more than 4,000 rpm, significantly reducing friction losses. It also features the latest iteration of Toyota's variable valve timing system. The automaker says the hybrid system cuts carbon monoxide, hydrocarbon and nitrogen-oxide emissions 90% and slashes carbon dioxide emissions in half. The Prius has achieved up to 66 mpg (3.5L/100km) in testing, Toyota says.

Also with an eye on the environment are the e-com and FCEV. The e-com 2-seater is a pure electric vehicle (EV), using a smaller-packaged version of the RAV4 EV powertrain. Toyota says the front-drive e-com's 24 12-volt nickel-metal hydride batteries can be charged using conventional household current (100v or more). The FCEV mini SUV is powered by a fuel cell that turns on-board methanol into hydrogen to produce electricity.

Toyota's NC250 4-door luxury sedan is similar to a BMW 3 series in size. It is rear-drive and features the automaker's experimental artificial intelligence(AI) automatic transmission. AI uses the navigational system, data from on-board sensors and driver inputs - such as braking - to control shifting. The NC250 also is loaded with safety features including stability control, brake assist and curtain shield air bags that come between front occupants and the car's side windows.

Likely destined for production is the MR-S, a mid-engine 2-seat roadster powered by a 1.8L 4-cyl., and the Harrier SUV/wagon hybrid - a thinly veiled concept version of an upcoming Lexus RX300 to debut in the U.S. in mid-1998. The Harrier offers full-time 4-wheel drive. Power comes from a 3L V-6 with variable valve timing. Also on the SUV front is the Grand Cruiser, a full-size model close to the Ford Expedition in size. Another model, simply called the New, is a hybrid that's more wagon than SUV.

Toyota also showcases a raft of engines with advanced variable valve timing systems, including a new 5L V-12 likely headed for the Toyota Century, an upgraded, 280-hp version of the 4L V-8 found in the Lexus LS400 and two 2L 4-cyl. engines - one with direct injection (DI). Two small DI diesels, a 1.5L and 2L, also were spotted in Toyota's corner.

Fuji Heavy Industries Ltd. shows off two new concepts, the Subaru Elten minicar and Exciga 6-seater wagon. The 4-door Elten seats four and features retro styling reminiscent of the first Subaru, the '58 360 model. It, too, boasts a hybrid gasoline/electric powertrain. The Exciga has a horizontally opposed DI gasoline engine and all-wheel drive.

Honda Motor Co. Ltd. takes the wraps off its "Integrated Motor Assist System." It combines a direct-injected 1L gasoline 3-cyl. the automaker claims can achieve 71 mpg with an ultra-thin motor/generator to provide additional power during acceleration. The combination provides the performance of a 1.5L engine, Honda says. The powertrain, linked to a continuously variable transmission (CVT) is featured in Honda's J-VX sports car concept unveiled at the show. Also on Honda's stand is a series of sport/utility and van concepts dubbed the J-MJ, J-WJ and J-MW, which feature a more conventional 1.5L engine and the CVT.

Four upcoming production vehicles and three new concepts light up the show for Mazda Motor Corp., including the revamped Miata. Dimensionally, the new Mazda remains virtually unchanged (a 0.2-in. [5-mm] gain in width the only modification). Both the 1.8L and 1.6L 4-cyl. engines get improved output and torque, and the bigger powerplant now is tied to a new 6-speed manual transmission. Dropped is the zipper around the rear window, making it easier to drop the top.

Also on the production side is a new Capella wagon, which gets what Mazda calls its "Diluted-burn" or "D-burn" engine - a 2L 4-cyl. that puts out fewer carbon dioxide and nitrogen oxide emissions and delivers better fuel economy. Mazda says this is achieved by recirculating large volumes of exhaust gas into the combustion chambers, reducing friction and lowering the combustion temperature. Other upcoming production models unveiled were the new MPV minivan and Bongo Friendee.

Mazda concepts included the MV-X multipurpose vehicle, SW-X space wagon and MX-X multipurpose sedan.

On the Nissan stand, Japan's No. 3 automaker used the event to showcase a range of DI gasoline and diesel engines, continuously variable transmissions, a new utility wagon and two mini cars.

The Japanese government's push for more environmentally friendly cars has not been lost at Nissan. The company's Hypermini, at 2,500 mm (98.4 ins.) in length, is an electric vehicle designed to carry one or two people for short trips around town. The front-wheel-drive car is 58 ins. (1,475 mm) wide and 61 ins. (1,550 mm) tall. Taking a page from the Chrysler Corp. design book, the vehicle's wheels are pushed to the outer corners to increase interior space and enhance the vehicle's stability.

The vehicle uses lithium-ion batteries that can travel 80.7 miles (130 km) on a single charge. The batteries are located under the floor pan. Top speed is 62 mph (100 km/h).

On the slightly larger side of its display stand, Nissan showed its Stylish 6 concept, a new-generation utility wagon that has the roominess of a minivan, but the handling and performance sedan owners will appreciate, Nissan says. The vehicle also features a hybrid drive system that uses a 2.5L direct injection V-6 gasoline engine and an electric traction motor, mated to a continuously variable transmission.

It also showed some new CVTs, including one that switches between automatic and 6-speed manual.