CONCORD, N.C. (AP) - NASCAR took the final step toward setting its 2014 rules package with a critical test session Wednesday at Charlotte Motor Speedway.
The test featured four simulated races with four configurations on the Gen-6 Sprint Cup Series car. Drivers had to attend a mandatory debrief with NASCAR following each session to give feedback on the aerodynamic, engine and suspension combinations.
NASCAR had 30 cars participating in the test, and planned to choose the configuration most favorable among drivers to test with a tapered spacer designed to reduce engine horsepower.
The goal of the test is to improve the racing at 1.5-mile superspeedways, which has been a stated goal of NASCAR Chairman Brian France. He was scheduled to attend the test Monday, but rain postponed it until Wednesday.
''Really what we're attempting to do here is to get closer competition and more passing, closer competition, the cars running closer in the pack, passing more with an eye for the fans,'' Gene Stefanyshyn, NASCAR's vice president of innovation and racing development.
''We're using various metrics to look at that, like the first to fifth time differentials, the time differentials between the 10 fastest laps, those types of things.''
NASCAR vice president of competition Robin Pemberton said the goal was to use the data collected Wednesday to set 2014 rules ''ASAP. Hopefully beginning of next week.''
Testing for the season-opening Daytona 500 begins Jan. 9 at Daytona International Speedway.
Among the four test car configurations on which data was accumulated and will be sorted through over the coming hours and days were:
-Splitters with a square leading edge.
-Skirts at four-inch minimum ground clearance on both sides of car.
-Rear fascia trimmed 1.375 inches higher in current scallop region.
-9-inch rear spoiler with 1-by-14-inch-wide end tabs.
-8.375-inch rear spoiler with 1-by-14-inch end tabs.
-1.5-inch high by 37.5-inch wide roof strip.
-43-inch wide by 13-inch long radiator pan.
-Intake manifold to throttle body plate that yields engine power of 750 horsepower
NASCAR tested six cars at Charlotte in October, and Stefanyshyn said Wednesday's test with actual races was critical to choosing the proper rules package.
''When it's all said and done, there is no wind tunnel where you can put 30 cars in, or (a computer model) where you can do that,'' he said. ''We do all that to get our best hypothesis or answer. But then really what it comes down to is 30 cars running around the track and seeing how it all works and measuring that.''