A 40's car roof line and aero is not quit the same as a any modern car. A 50's fast back isn't either. A vacuum is the cause and it need to be broken. Air vents were the remedy for many years are still correct today. With the rules today, a picnic table or garage door hanging on the trunk is what is being used, but some correct holes and duct works and look a lot better. At 152.90 with some nitrous and a sealed grille made us feel we reached the pinnicle of success with our 40 Chev coupe especially with 6 cylinder power.