A demolition derby has been added to the regular nine-race stock car program at Beltsville Speedway tonight. For the late-model sportsman sedans, it will be the last prep before next Friday night's $15,000 Coca-Cola 200-lap national point event. Beltsville time trials start at 7 p.m., racing at 8.

The Winston 150-lap race for the late-model sportsmen will be run at Old Dominion Speedway, near Manassas, tomorrow. It's worth double points, so defending national late-model champion Butch Lindley of Greenville, S.C., has entered. Two main events for the street stock sedans also are scheduled. Time trials are at 7 p.m. racing an hour later.

Dirt-track stock-car racing is set for tomorrow night at Dorsey, Md., which also has figure eight races and street stock events, and at Potomac Raceway, Budds Creek, Md. Racing begins at 7:30 p.m. at both tracks.

Motorcycle races will be run over the Dorsey quarter-mile tonight at 8. Drag racing is at Maryland International's quarter-mile strip at Budds Creek tomorrow night at 7:30.

Road-racing fro motorcycles is scheduled for tomorrow and Sunday afternoons over the two-mile Summit Point, W. Va., course. The next road-racing meet at that track is the Super-Nationals Sports Car Club of American event Aug. 26 and 27.