Toyota and the German carmaker would adapt the gasoline-electric powertrain to be used in the Lexus RX 400h, the source told Automobilwoche. The RX 400h, based on the Lexus RX 330, is slated to go on sale in the United States in December.
The Porsche source says the automaker is conducting feasibility studies for a hybrid Cayenne.
Porsche has said it won't offer diesel models, so it needs an alternative powertrain that uses less fuel and emits less pollution.
Porsche needs to meet tougher tailpipe regulations 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 No. 1 sales market.
Toyota thinks the 270hp system on the RX 400h is suitable for the Cayenne. "The system in our Lexus SUV would fit well on the Cayenne," says a Toyota manager, who adds that Toyota's aim is to spread its hybrid technology worldwide.