Hefty incentives offered by Toyota to rejuvenate sales and market share -- and copied by some competitors - sent U.S. industry sales soaring in the early going of March, according to Edmunds.com's forecast.

In the first eight days of March, the Seasonally Adjusted Annual Rate (SAAR) of U.S. sales climbed to 12.5 million units, the highest level since September 2008, excluding August 2009 when Cash for Clunkers was at fever pitch.

"Generous incentives from Toyota and General Motors have stimulated this boom," Edmunds.com Senior Analyst Ray Zhou, PhD. "But we anticipate that it will cool off, and that the month will end closer to 11 million or so."