Subaru executives expect to learn soon whether Toyota will build a vehicle at Subaru's underused plant in Lafayette, Ind.
The companies are studying a plan to build either a car or SUV at the plant.
Subaru hopes to offset the loss of a small Saab crossover based on the Subaru Tribeca that was to be produced at the plant.
General Motors canceled that plan in October when it sold its 20 percent stake in Fuji Heavy Industries Ltd., Subaru's parent company.
Toyota Motor Corp. later acquired 8.7 percent of Fuji Heavy. Fuji and Toyota then set up a committee to study what Toyota could produce at the plant.
"Our collaboration with Toyota is becoming very successful, and we are looking forward to maximizing capacity at our Indiana plant," Ikuo Mori, senior vice president at Fuji Heavy Industries said at the Detroit auto show.
The plant, which has capacity for 240,000 units, formerly was a joint venture between Subaru and Isuzu.
Isuzu sold its 49 percent stake to Fuji Heavy in 2003 but continued to build its Rodeo pickup and Axiom SUV there until July 2004.
Subaru uses only 50 percent of capacity.
The former Isuzu assembly line is used for some Tribeca production. Subaru also produces the Legacy/Outback and Baja cars at the plant.