German luxury carmaker Porsche (search) has asked Japan's Toyota (search), the world's second-largest automaker, to share the hybrid technology used in its popular Prius (search) model, a Japanese newspaper said on Tuesday.

Toyota is taking a positive view of the proposed deal and expects to start negotiations soon, the Asahi Shimbun said without citing sources.

In Stuttgart, a Porsche spokesman reiterated that the company was still studying the use of hybrid technology.

"We are investigating the technical feasibility of this kind of powertrain. This is an extremely interesting alternative to diesel engines," he said.

Toyota's hybrid engines incorporate an electric motor alongside a gasoline engine. The motor is used for low-emission driving in the city, while the gasoline engine kicks in at higher speeds on the open road.

Porsche is likely to want to use the technology in its Cayenne offroader, rather than in smaller sports models, the Asahi said. Developing its own hybrid technology would be difficult for a relatively small company, the paper said.

Germany's Automobilwoche paper reported last month that Porsche was eyeing the 270 horsepower petrol-electric powertrain to be used in the RX 400h SUV made by Toyota's premium Lexus division.

The RX 400h, based on the Lexus RX 330, is set to go on sale in the United States in December.

The Prius's hybrid engine would probably not be powerful enough to drive the 250 horsepower Cayenne.

Toyota, which became the first company to mass market a gasoline-electric hybrid in 1997, has already sold its technology to Nissan and Ford, the Asahi said.

No one was available at Toyota for comment on Tuesday, a national holiday.

Hybrid technology could help Porsche meet tougher environmental standards in Europe and the United States, where rule changes are beginning to take effect.

Stricter U.S. emissions regulations will be phased in through 2009. The United States is Porsche's primary sales market.