Thanks to the persistent popularity of the Prius among American drivers, who buy 65 to 70 percent of all Toyota hybrids sold worldwide, the company is considering developing a bigger, badder version of the gas-sipper. James E. Lentz III, the head of Toyota Motor Sales USA, says he has proposed creating a separate Prius brand akin to the auto giant’s Scion spin-off. The new line, which would be sold in regular Toyota dealerships and available only in the U.S., could include various sizes — including, said Lentz, “one on steroids.” Sa-weet! Company officials, who recently announced the long-term possibility of converting their entire high-end Lexus line to hybrid models, are said to be mulling over the idea. “We’re catching the wind on this,” Lentz said. Or is that the breeze from a thousand F150 owners laughing?