How Will a Roof Rack Affect Your Car’s Fuel Efficiency?

Thinking about adding a roof rack to your car? Whether you're gearing up for a cross-country road trip, planning weekend adventures, or just need more cargo space, roof racks can be incredibly helpful. But before you bolt one on and load it up with bikes, kayaks, or luggage, theres one important thing you should knowroof racks can affect your cars fuel efficiency.

In this blog, well break down how and why that happens, the extent of its impact, and what you can do to reduce the fuel efficiency drop while still enjoying the benefits of extra storage. Lets dive in!

What Is a Roof Rack?

A roof rack is an external structure mounted to the roof of a vehicle, designed to carry items that may not fit inside the car. This could include bikes, skis, luggage boxes, kayaks, or even construction materials. Roof racks come in a variety of styles, such as:

• Crossbars and rails

• Basket-style carriers

• Cargo boxes

• Specialty mounts for sporting equipment

While a roof rack expands your cargo options, it also changes the way your car interacts with the air around itwhich brings us to the key point of this article: aerodynamics and fuel efficiency.

How Does a Roof Rack Impact Fuel Efficiency?

1. Increased Wind Resistance (Drag)

When your car moves, it has to push through the air. A sleek vehicle without add-ons moves more easily, requiring less fuel. Add a roof rack, and your vehicle becomes less aerodynamic. This results in increased drag, which means your engine has to work harder and consume more fuel to maintain speed.

Even an empty roof rack contributes to wind resistance. Load it with bulky gear or an enclosed cargo box, and the aerodynamic profile takes an even bigger hit.

In simple terms:
More drag = more fuel consumption.

2. Added Weight

Although roof racks themselves are relatively lightweight (usually between 1040 pounds), the items you place on them can add substantial weight to your vehicle. The heavier your car, the more fuel it needs to move.

And dont forget: adding weight to the top of your car also raises the center of gravity, which may affect handling and stability, especially when turning or in windy conditions.

3. Reduced Efficiency on Highways

The faster you drive, the more aerodynamic drag matters. At highway speeds (60+ mph), even a small roof rack can lead to a noticeable drop in fuel efficiency. Various studies have found that a roof rack with cargo can reduce fuel economy by 10% to 25%, depending on the shape and weight of the items.

For example:

• A compact car with a roof box at 65 mph may lose 15% or more fuel efficiency.

• An SUV with bikes on the roof might lose up to 25%.

If you do a lot of long-distance or highway driving, its worth calculating the extra fuel cost over time.

Real-World Fuel Efficiency Stats

Lets put the impact into perspective with some estimated examples:

Note: These numbers are averages and can vary based on the shape of the load, driving speed, terrain, and vehicle design.

How to Minimize the Impact of a Roof Rack on Fuel Efficiency

The good news? There are ways to reduce the effect of your roof rack on gas mileage:

1. Remove the Rack When Not in Use

This might seem obvious, but its one of the most effective tips. If you're not using the roof rack, take it off. Even an empty rack creates drag. Some studies suggest that removing an unused roof rack can restore up to 5% of your lost fuel economy.

2. Use a More Aerodynamic Setup

If you need a cargo box, choose one with a sleek, aerodynamic design. Slim, tapered cargo boxes are far more fuel-efficient than wide, boxy ones. Similarly, low-profile bike or ski racks reduce wind resistance.

3. Pack Light and Low

Avoid loading heavy or tall items on top. Keep cargo weight as low as possible, and if you can fit gear inside the car, do it. Try to limit roof loads to lighter, bulkier items only.

4. Drive Slower

Every extra 10 mph above 50 mph significantly increases drag. Slowing down from 70 mph to 60 mph can make a meaningful difference in fuel efficiency when youre driving with a loaded roof rack.

5. Consider Rear-Mounted Carriers

When possible, use a hitch-mounted cargo carrier or bike rack instead of placing items on the roof. Rear-mounted carriers dont affect aerodynamics as drastically, especially on tall vehicles like SUVs.

Is a Roof Rack Worth It?

It depends on your needs. If you regularly carry bikes, kayaks, or gear that wont fit in your vehicle, a roof rack offers freedom and flexibility. But if you only use it a few times a year, its smart to weigh the fuel costs vs. the convenience.

Heres a quick breakdown:

Pros:

• Expands storage capacity

• Frees up space inside the vehicle

• Ideal for outdoor adventures and long trips

• Great for transporting awkward items (bikes, skis, etc.)

Cons:

• Reduces fuel efficiency

• Increases wind noise

• Can impact handling and vehicle height

• Requires careful loading and securing

If fuel savings are a major priority, consider alternatives like:

• Roof bags (only when needed)

• Hitch-mounted storage

• Compact trailers

Read More...

FAQs

Q1: Does an empty roof rack still affect fuel efficiency?

Yes. Even an empty roof rack creates extra drag, especially at higher speeds. The loss might be small (around 35%), but it adds up over time. Removing the rack when not in use can help you save fuel.

Q2: How much fuel does a roof box use?

A loaded roof box can reduce your fuel economy by 1020%, depending on the size, shape, weight, and driving speed. Choosing an aerodynamic box and packing light can minimize this impact.

Q3: Is it better to use a roof rack or a hitch rack?

In terms of fuel efficiency, hitch racks tend to be more efficient. They stay behind the vehicle, reducing drag and turbulence. However, they may block access to your trunk or require a tow hitch to be installed.

Final Thoughts

A roof rack is a practical and often necessary accessory for many drivers, especially those who love the outdoors or travel frequently. However, its essential to note that it can impactyour cars fuel efficiency, sometimes significantly.

The good news? By being mindful of how you use your roof rack, what you carry, and how often it's installed, you can reduce its impact on gas mileage. Think of it this way: smart roof rack use = more adventure, less fuel cost.

So go ahead, load up and hit the roadbut do it wisely!