With the success of the Toyota Prius, a gasoline-electric hybrid compact that debuted in 1997, such models have become a major focus of an automotive industry eager to clear tougher environmental regulations and improve its image.

Following the path of carmakers, minivehicle and truck manufacturers are also getting on the hybrid vehicle bandwagon, providing greater choices to consumers.

"Hybrid vehicles can become attractive for customers seeking something new," said Seiji Sugiura, an industrial analyst at Nomura Securities Co.

But industry experts also say that newcomers to the hybrid market face a tough challenge -- introducing hybrid minicars and trucks at competitive prices.

Many drivers choose minicars, which come with engine displacements up to 660cc, over compacts because minicars are highly economical due mainly to their low price, high fuel efficiency and preferential tax treatment.

Truck buyers, many of them companies, have meanwhile been forced to slash expenses amid the continued economic slump.

Thanks to its fuel efficiency, Suzuki Motor Corp.'s Twin Hybrid, Japan's first commercial hybrid minicar, has proved popular since its January debut, boasting some 200 orders. The initial annual sales target was 100 units.

Hybrid cars are essentially powered by an internal-combustion gasoline engine, but an electric motor provides added power during ignition and when the car is running in low gear. When braking, the engine charges the electric motor and stores surplus energy in a battery. The engine automatically shuts off when the vehicle is idling to conserve fuel.

The two-seat Twin Hybrid gets 34 km per liter of gasoline, compared with its conventional gasoline-powered base model, which gets 26 km per liter, according to Suzuki.

The carmaker has yet to decide if it will expand the hybrid technology to other models, including the popular Wagon R and the Arto, because it is not sure whether expensive hybrid models will induce minicar customers to step up.

Suzuki President Hiroshi Tsuda said consumers would widely accept hybrid models if they are priced no higher than 20 percent more than nonhybrid cars. However, the Twin Hybrid sells for between 1.29 million yen to 1.39 million yen, up more than 450,000 yen, or more than 54 percent, from the base model.

"We don't want to generate losses by selling hybrid cars," he said in explaining why Suzuki's hybrid model is so expensive. "We're not sure how the public will evaluate the hybrid model, so we set the annual sales goal of the model at 100 units."

Tsuda said the minivehicle maker will spend a year analyzing consumer data and then gradually introduce hybrid versions of other minivehicles and compacts.

Truck and bus makers are now introducing diesel-electric hybrids in time to meet tougher regulations taking effect in October by local governments in the Tokyo metropolitan area on nitrogen oxide and soot emissions from diesel-powered vehicles.

Hino Motors Ltd. plans to release the 2-ton hybrid truck Dutro in October and Mitsubishi Fuso Truck & Bus Corp. will launch a hybrid bus at the end of the year and a 2-ton hybrid truck next year.

The price issue also haunts truck and bus manufacturers.

Nissan Diesel Motor Co. last June debuted the Condor Capacitor Hybrid, a 4-ton hybrid truck that boasts a 50 percent improvement in fuel consumption, a 33 percent reduction in carbon dioxide emissions, a 44 percent cut in nitrogen oxide and a 66 percent drop in soot compared with the diesel-powered base model.

But it has only sold two units of the hybrid so far.

The hybrid truck is priced at 14.4 million yen -- 9 million yen more than the conventional diesel-engine model. Although buyers of any hybrid model can receive government subsidies to cover half of the price gap, the cost is still extravagant.

Kiyoshi Minami, general manager at Nissan Diesel's product project office, noted that the hybrid's high price is due to the cost of the electric motor and capacitor electricity storage device.

"If we can sell more hybrid trucks, we can lower manufacturing costs and prices," he said, adding the company needs to sell 30 units annually to break even.

Despite the difficulties, manufacturers of minivehicles and trucks continue to try to develop better hybrid models, and the market is only expected to grow.

In December, Hino Motors, with the help of major parcel firm Yamato Transport Co., began studying driving patterns of delivery drivers using its Dutro truck.

"By collecting data on the driving patterns of Yamato's parcel deliverers, we can learn how we should program the combination of using a diesel engine and an electric motor" to further improve fuel efficiency, Hino spokesman Shigemi Omori said.

He said hybrid trucks can effectively reduce carbon dioxide emissions, a major cause of global warming, unlike a low-cost diesel particulate filter. Attaching the filter to a diesel truck can cut nitrogen oxide and soot effectively, but it will not reduce carbon dioxide output.

Suzuki is also conducting feasibility studies on other hybrid models.

"Other carmakers plan to produce various hybrid vehicles, so we must keep up," Suzuki's Tsuda said.

According to Nomura Securities, the global hybrid vehicle market is expected to reach about 1.5 million units by 2007 from 60,000 in 2002.

Nissan Diesel's Minami said hybrid trucks have the advantage of not requiring special gas stations and predicts they will spread on the market faster than condensed natural gas-powered vehicles, another environmentally friendly truck that can reduce nitrogen oxide and soot emissions drastically.

"Though our first midsize CNG truck, which went on sale in 1994, was as expensive as the current hybrid truck, we could sell about 150 CNG midsize trucks in 2002," Minami said. "Unlike CNG vehicles, hybrid vehicles can be filled at existing gas stations, so I think hybrid vehicles can spread faster."