With the new Next Gen car, NASCAR continues to tweak the rules to enhance competition on the track.

Beginning with the one mile track of Phoenix Raceway, the cars will feature a new aerodynamic package for the short tracks and road courses.

The new package is in conjunction with the wet weather package and will decrease the downforce on the cars.  The package includes a shorter spoiler from four to two inches, removal of three diffuser strakes, and trimming the diffuser’s outer fencing.

The changes were introduced after a track test in January and will result in an approximate 30 percent reduction in downforce.  The package was originally inspired by the NASCAR’s Garage 56 program as NASCAR, Hendrick Motorsports, and Chevrolet work toward preparing a car for the 24 hour endurance race at Le Mans.

Another new addition to the cars affect only races within city limits – Los Angeles and Chicago – for The Clash and the street race that includes noise dampening mufflers to reduce the noise six to 10 decibels.  The mufflers will also alter the aerodynamics of the cars.

The half mile track at Bristol and the Monster Mile in Dover are not included in the tracks where the new package will be used.