I never liked the amount of smoke by the game while spinning your tires, locking your brakes up and sliding around.
So I just reduced it with editing the original smoke texture. There are different percentages available, from 25%,30%,40% to 50% of the original smoke amount.
I use the 25% version and still think it might be a bit much...let me know what you think and I might load up some even lower amounts.
Installation: Just put the resources.assets file in steam/steamapps/common/Nascar Heat Evolution/NascarHeatEvolution_Data/...
Don't forget to backup your original file.