Yes, holiday car decorations creates aerodynamic drag.
GM found:
- Antlers. Reindeer antlers and Rudolph’s nose create about a 1-mile-per-gallon decrease in highway fuel efficiency and a 3% increase in drag coefficient — commonly understood as air resistance.
- Bow. A roof-mounted bow creates a 3.5-mpg decrease in highway fuel efficiency and a 15% increase in drag coefficient.
- Christmas tree. A tree tied to a roof creates a 30% decrease in highway fuel efficiency and a 70% increase in drag coefficient. Air pushes against a tree with about 90 pounds of force.
- Wreath. A grille-mounted wreath has no impact on aerodynamics but may reduce cooling airflow to the engine.
