The Japanese auto maker said it plans to double its annual production at a car plant now under construction near Alliston, Ontario. The move to increase production to 80,000 cars a year by 1989 will also involve doubling its capital investment to $200 million (Canadian). The company originally estimated that it would be producing 40,000 units annually by 1989. Construction of Honda's plant started in November, 1984, and is scheduled to be completed by the summer of 1986, with production slated to begin in late 1986. Current plans call for an annual output of 30,000 cars by 1987.