WASHINGTON (AP) _ Federal engineers opened investigations into reports of safety defects in up to 200,000 Subaru cars and Nissan trucks, the National Highway Traffic Safety Administration said Thursday.

The investigations, both preliminary evaluations, involve complaints of engine fires in 1987 Subaru DL and GL models and complaints of steering problems in 1987 to 1989 Nissan pickup trucks. Preliminary evaluation is the lowest level of investigation conducted by NHTSA engineers when they receive complaints.

NHTSA said the government received five complaints from Subaru owners of engine compartment fires. It estimated that 67,000 of the cars are on U.S. roads.

Two owners wrote to complain of steering problems in the Nissan vehicles, including one that resulted in an accident with injuries, NHTSA said.

The safety agency said one complaint involved a locked steering wheel and the other a loss of steering control.

Engineers will determine whether evidence warrants an upgrade of their inquiries to engineering analyses which would invovle actual inspection of the vehicles.

NHTSA, in its monthly Defect Investigation Report, also announced upgrade of its investigation involving more than 640,000 Ford Taurus and Mercury Sable 1986 and 1987 cars.

An engineering analysis will be conducted into the possibility of broken or cracked front seat brackets in the cars, following 68 complaints received by Ford Motor Co. and the government.

A substantial number of motorists have lodged warranty complaints involving the seat brackets, NHTSA said.