The plant now employs about 3,600 people and builds the Legacy and Outback cars and the Tribeca SUV. It also builds the Camry midsize car under contract with Toyota Motor Corp., the top shareholder in Subaru with a 16.5 percent stake.
Subaru, also known as Fuji Heavy Industries, said it will boost capacity at one of two assembly lines at the plant -- the one that is now being used to build the Camry -- from 100,000 vehicles to 200,000 vehicles.
It had already announced it would boost production capacity at the other line from the current 170,000 vehicles to 200,000.
Production of the Impreza is expected to start by the end of the 2016, said Subaru spokesman Yoshiaki Tabei.
Subaru sold 724,500 vehicles globally for the fiscal year ended March, up 13 percent from the previous year, with 357,600 of them in the U.S. It sold 163,100 vehicles in Japan.
Subaru's U.S. sales have doubled in the past five years.
U.S. sales of the Impreza, now built in Gunma, Japan, have fallen 31 percent this year, due largely to a shortage of vehicles on dealer lots. Ward's Automotive says Subaru has only enough Imprezas on the ground to supply dealers for 29 days. A 60-day supply is considered optimal.
For the fiscal year ended March 31, Subaru sold 108,000 Impreza cars in the U.S., all imported from Japan.