Bloomberg reports that Toyota Motor may extend the Prius into a line of vehicles as the company tries to triple annual US sales of hybrids.

The US will account for more than half of the 1 million hybrid cars and light trucks Toyota plans to sell worldwide each year by early next decade, Jim Lentz, Executive Vice President of the company’s U.S. sales unit, told Bloomberg in an interview at the Specialty Equipment Market Association (SEMA) show in Las Vegas. Prius-based models might include a wagon and a smaller car, he said.

“For us to do 600,000, there will probably have to be Prius and derivatives of Prius that are selling in the neighborhood of 300,000 to 400,000...We don’t have any plans to do that right now, but that’s the direction that nameplate can go, because it is that strong.”

In 2005, Toyota sold 235,000 hybrids worldwide—about four times as many as Honda, which ranks second in such sales.

“To the extent they can leverage derivatives to help amortize investment costs for the hybrid system, they’d be crazy not to,” said Eric Noble, president of consulting firm Car Lab in Orange, California. “There is so much equity in the Prius name at this point, that would make sense, especially in the near term.”

A smaller “city car” based on the Prius would have even higher fuel efficiency and would fit with “a trend toward people moving into inner-city lofts,” Lentz said. “People also want to see more utility on the vehicle, so you could imagine something that’s a little more utility or crossover-based.”