The greater the speed of any given shape, the greater the drag. Though reducing drag is extremely important for Winston Cup teams at high-speed tracks like Daytona and Talladega, it is a factor in virtually all forms of racing, including short track. Air Dam Adjusting the air dam. The purpose of this strip is to prevent as much air as possible from getting under the car. Once under the car the air rolls and buffets, creating drag that slows the car.
Cars also use the apron to accelerate up to speed when re-entering the track from the pit area.
If a car is moving relatively slowly, going from the track onto the apron presents no problems. At racing speeds, however, running even one wheel accidentally onto the apron can easily cause the driver to lose control. The cost of sponsoring a typical Winston Cup or Busch car is very high to say the least, often in excess of 10-million dollars in Winston Cup. Adding several Associate Sponsors can greatly increase a teams operating budget. The front wheels also have weight jack screws, and turning them has the same affect as turning the rears, but the fronts are not accessible during a race so they are not adjusted during pit stops.