LOS ANGELES --- Toyota Motor Corp. plans to have a plug-in version of the Prius for sale in the U.S. within the next three years, a company executive confirmed during an appearance at an environmental conference. 

"The target is 2012 to be coming to market with them," Irving Miller, group vice president for Toyota's U.S. sales unit, said at a climate change conference held in Los Angeles, Bloomberg News reported. Prior to that, the automaker will "study the challenges of consumer demand." 

Previously, Toyota had announced plans to bring 150 plug-in Priuses to the U.S. fleet market before the end of this year. 

The automaker is taking perhaps a more restrained approach than some competitors in the EV market, but that caution is rooted in experience. During his talk, Miller acknowledged that early buzz for electric vehicle introductions isn't always an accurate measure of genuine sales prospects. 

"We had a lot of people raising their hands for the RAV4 EV," he said. "As soon as we made them ready for sale, that line evaporated very quickly."