Does A Roof Rack Reduce Fuel Economy?

Roof racks can significantly impact fuel economy, depending on the roof rack type, the speed you’re driving, and the car’s size. For example, a small roof rack on a sedan driven in the suburbs may not significantly impact fuel economy, while a large roof rack on an SUV on the open freeway may.

What Are Roof Racks?

Roof racks are a special type of device specifically designed and attached to the rooftop of a vehicle using various connecting systems to transport very bulky items such as bikes, tents, bags, and much other equipment.

With a roof rack fitted on a vehicle, some of these bulky items can be moved from the vehicle trunk or the back seat and placed on the roof, expanding your vehicle’s cargo-carrying capacity.

What Are The Different Types Of Roof Racks?

There are various types of roof racks. We will take you through the different types of roof racks in this article and provide you with a guide on how to check the roof racks that are the best fit for your car and how to install them.

Family Road Trip - Do Roof Bars Reduce Fuel Economy?

Square Roof Racks

This is a simple type of roof rack, made from steel with a square bar shape. It is usually very cheap.

Aluminum Roof Racks

This is a type of roof rack made from aluminum. It is lighter in weight and has several aerodynamic properties. They should be corrosion-resistant and capable of withstanding extreme weather.

Thule Aero Roof Bars

Thule AeroBlade roof racks are specially designed roof racks by Thule that have aerodynamic properties. They are made from aluminum and employ WindDiffuser technology to disturb airflow to reduce noise and drag for improved fuel economy.

Effects Of Roof Racks On Fuel Economy

The addition of a roof rack on any vehicle can affect fuel economy.

It’s important to understand the fact that any adaptation that leads to a change in the body shape of a vehicle automatically affects the vehicle’s economy. When you put a roof rack on your car, it sticks out higher than the vehicle’s normal roof line and changes how air flows around it.

When you drive with an addition to your roof, be it just the rack or the roof rack with a basket, a cargo bag, or a cargo box attached, the car has to work harder against the wind, which uses more fuel. This extra effort against the wind is called “wind drag.”

Wind drag, or wind resistance from a roof rack can be a significant factor in the fuel economy of both sedans and SUVs.

When a roof rack is installed, especially if it’s carrying bulky items, it disrupts the vehicle’s aerodynamics. This means the vehicle has to work harder to move forward, leading to increased fuel consumption.

While SUVs are generally less aerodynamic than sedans to begin with, adding a roof rack can still negatively impact their fuel efficiency.

Should I Remove My Roof Rack When Not In Use?

It’s always a good idea to remove roof racks when not in use to maintain the best possible fuel economy.

It can be a bit of a pain, especially if you are using your roof rack regularly, but yes, the consensus from motoring experts is that you will save fuel by removing your roof racks when not in use.

Sources:

How Do I Know The Best Fit Of Roof Racks For My Car?

Normally, most roof racks are designed specifically for a specific type of car. This is the case with cars that have factory-fitted roof racks installed. However, for plain roof types of cars, it’s always important to check for compatibility with the car before purchasing.

Furthermore, ensure to check for the properties of the roof rack. Some of the properties to check for before purchasing and installing a roof rack include;

The Roof Racks’ Weight Limit

Roof rack manufacturers always have the specific weight limit of the rack boldly specified in the manual. Roof racks have varying weight capacities of 50kg to 100kg (100 lbs – 220 lbs). It’s important to note that car roofs, which are usually made from aluminum, also have their weight limits. 

To this effect, also check the car’s manual to help in your decision-making about the type of roof rack that best fits your car.

Understand Aerodynamics

Additionally, packing items in streamlined cargo boxes rather than letting them sit exposed can help reduce drag and improve fuel efficiency. Hard roof boxes may cost more than soft structured roof bags, but you should also consider the longer-term fuel saving.

  • Are you worried your roof racks or cargo carrier may not be installed correctly, and they’re making too much noise? Check out our problem-shooting guide to reducing noise from your roof racks

Tips On Roof Rack Installation

Many people usually wonder if they can install these themselves. The answer is YES – but take care.

Roof rack installation is a simple DIY task that one can easily carry out with the right tools. Here is a list of tips that can guide you through the process of correct roof rack installation;

1. Ensure to Get a Helping Hand or an Assistant

This will help you carry out the job easily and quickly while reducing the chance of accidents and damages; unless you’re extra tall and strong, lifting items above your vehicle requires a fair bit of work and muscle power.

2. Carefully And Thoroughly Study the Instructional Manual 

There is a reason why manufacturers go through the process of printing instruction manuals for their products. These manuals are significant as they contain critical and essential information about your car and the impact of add-on accessories.

3. Carefully Clean Up The Car Roof

Using a soft piece of cloth, mild soap, and water, thoroughly clean the car door. This is essential, especially for cars whose roof racks must be positioned close to the door jamb. Having dirt latched in between the points of contact of the car roof and the roof rack could lead to scratches on the car paint.

4. Apply Lubricants 

The application of lubricant on the bolts of the roof racks helps to keep them away from rusting. Also, it guarantees a smooth removal of the roof racks anytime you desire.

5. Observe The Torque Settings Of Your Roof Rack. 

Ensure to study the instructions while observing the Torque settings carefully. It is always advisable not to over-tighten your roof racks as this may damage the rack or the car.

However, it is important to note that roof racks come in three distinct parts, considering the unique nature of cars in shapes and sizes.

These parts are;

  • The Roof Bars
  • The Foot Packs that are usually attached to the bars
  • And the fitting kits. This kit is used for binding the feet to the roof.

Most cars often require three parts for attaching the roof racks to the cars. In addition, vehicles with factory-fitted rails or open rails may only require the roof racks and the foot packs for attaching the roof racks.

Other Ways to Make Your Road Trip More Fuel Efficient

Whilst we have identified that roof racks and their attached load can reduce fuel economy, it’s also worth bearing in mind these steps to improve your fuel economy when you hit the road:

  • Make sure your vehicle is well-serviced and tuned before your road trip
  • Check you are using the correct tires and they are inflated correctly
  • Minimize the number of RPMS and keep your speed in check – higher velocity (i.e. driving faster) creates more wind drag
  • Use cruise control, if your vehicle is fitted with this feature
  • Do not overload your roof rack

Transporting Bikes?

Bikes on a rooftop carrier can be up to four times less fuel efficient than bikes carried on the rear of a vehicle on a hitch mount. We will cover these later in our cargo-carrying series here on Family Road Trip.


In conclusion, with an additional weight on a vehicle, there will be an effect on the fuel economy. However, due to the insignificant weight of the roof racks themselves on a vehicle, the reduction in fuel economy can be minimized by using an aerodynamic roof rack such as Thule AeroBlades.

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