The Impact of Ski Racks on Aerodynamics and Fuel Efficiency

Ski racks are a lifesaver for winter sports enthusiasts, letting you transport your gear to the slopes with ease. But have you ever considered the impact these racks have on your vehicle's aerodynamics and fuel efficiency? From roof-mounted ski racks to hitch racks and roof boxes, each option alters the way your car interacts with airflow, potentially reducing your miles per gallon (MPG). Here’s a breakdown of how they affect your ride and how you can optimize their use.

Roof-Mounted Ski Racks

Roof-mounted ski racks are a popular choice due to their accessibility and ability to accommodate multiple skis or snowboards. However, they also have the largest impact on aerodynamics. Adding a roof rack increases the drag on your vehicle, disrupting smooth airflow. When skis are added, the irregular shapes further complicate this, leading to an MPG decrease of 10-25%, especially at highway speeds.

For example, research shows that simply attaching a roof rack increases drag force by over 9%. Adding skis—with either the tips or tails facing forward—increases drag further. While placing skis tails-forward is slightly more aerodynamic, the best way to mitigate fuel loss is to avoid a roof rack altogether when not in use. But do you really want to take your roof rack on and off your car all winter?  For solo trips, placing skis inside the vehicle can save fuel without sacrificing comfort, but does risk damaging the car interior.

Hitch-Mounted Ski Racks

Hitch-mounted racks are an alternative that could reduce the drag penalty. Since they attach to the rear of your car, they don’t interfere with airflow over the roof. On average, a hitch-mounted rack reduces MPG by 5-15%, which is less significant than roof racks. However, this still depends on the weight and design of the rack and the skis you’re carrying.

One advantage of hitch racks is their lower height, allowing for easier loading and unloading compared to a roof rack. If you frequently hit the slopes, a hitch rack might be your best option for preserving aerodynamics and saving on fuel.

Roof Boxes

Roof boxes are sleek, covered compartments that offer better protection for your gear compared to open racks. While their streamlined shape helps reduce some air resistance, they still increase drag significantly. An empty roof box might lower MPG by 2-8%, while a fully loaded box can result in 10-25% reductions, similar to roof-mounted ski racks.

The real advantage of roof boxes lies in their secure design. Gear is protected from weather, dirt, and UV exposure. For long trips with multiple passengers, this can be a worthy trade-off, as long as you remove the box when it’s not needed to minimize drag.

Practical Tips to Optimize MPG

1. Remove When Not in Use: Whether it’s a roof rack, hitch rack, or roof box, uninstall it when driving without skis to reduce unnecessary drag.
2. Drive Slower: Drag increases exponentially with speed. Slowing down on highways can save fuel.
3. Pack Wisely: If possible, fit skis inside the car to avoid using external racks.

Bottom Line

While ski racks make winter adventures possible, they come with a trade-off in fuel efficiency. Roof-mounted options impact MPG the most, while hitch racks are  less taxing. Using a hitch rack when you hit the slopes help both with costs and the environment.