Al Unser has won only three U.S. Auto Club (USAC) championship races for Indianapolis-type cars this year but they have been the trio of 500 milers on the schedule.

He's now close to a half-million dollars in winnings this season and his second national title. In 1970, when he took his first crown, Unser won 10 of 18 races on paved and dirt tracks.

Baltimore stock car driver Van Hatchell is not one of the front-runners at Beltsville Speedway, a fact that may have saved Dick Boswell of Berwyn Heights, Md., a contender, from serious injury.

On the second lay of last week's 200-lap race there, Boswell's steering evidently broke and he drove straight into the first turn's steel fence. He was pinned in his car, the engine aflame.

When trailer Hatchell arrived, he immediately stopped his car, backed up and across the track to block on-coming cars from hitting Boswell who, it turned out, was uninjured. It took two tow trucks to pull his wrecked car from the entangling steel rail.

George Underwood of Forestville, Md., a stock car driver, is running off the track now. He's a candidate for sheriff of Prince George's County, his second try for the post. A scrap-metal merchant, Underwood uses the same car to race on paved and dirt tracks.

The biggest race meet for tiny cars is next Sunday's invitational event for radio-controlled racers. The wafer-thin machines will compete over a twisting road course at the Tyson's Corner mall parking lot, starting at 8:30 a.m.

Bob Tullius of Herndon successfully defended his Trans-Am Category I road-racing title by winning his fourth straight race, at Mosport, Canada. He drives the only Jaguar V-12 in the national series for mass-produced cars with limited modifications.

An all-time speed record was set over Maryland International Raceway's quarter-mile drag strip recently when Fred Goeski of Los Angeles covered the distance in 4.68 seconds from a standing start. His rocket-powered, plastic-bodied Funny Car hit 249.95 miles per hour through the timing trap at the finish.

Major fall racing events include the Sports Car Club of America road races at Summit Point, W. Va., Sept. 16-17; the 500-mile stock-car Grand National at Dover, Del., Sept. 17; motorcycle road races there, Sept. 23-24; a USAC 150-miler for Indianapolis cars Sept. 23 at Trenton, N.J.; the Race of Champions for modified stock cars Sept. 24 at Pocono, Pa., and the Grand National event at Martinsville, Va., the same day.

The U.S. Grand Prix is Oct. 1 at Watkins Glen, N.Y., and the national amateur road-racing runoffs Oct. 22-29 over the Road Atlanta course.