Saab Automobile AB may build a new car that would fall under the 900 by the end of the decade, says Keith O. Butler-Wheelhouse, president and CEO. "I think it would likely be smaller than larger," he says. "But that is going to depend a lot on what happens in the market. It depends on how the new smaller luxury cars from Mercedes andand Audi do. They may play well in Europe and not play well here." The 900 currently is priced between $24,000 and $40,000. Meantime, Saab expects to improve its overall North American sales volume by 50% over 1994 levels, topping 35,000 units in 1995, says James Crumlish, CEO of Saab Cars USA, Inc. The automaker's target is 50,000 sales here by the end of the decade.