A roof basket or even a cargo carrier makes the ideal accessory for overland adventures. A question that often crops up about these gadgets is this: do roof racks affect gas mileage? Many people report an decrease in gas mileage when adding roof racks to their vehicles. This is not surprising, seeing as these devices do decrease the mile per gallon ratio.
Understanding why fuel efficiency decreases, and how to combat it, makes life simpler. So you can enjoy your roof rack system and the journeys you take it on.
Understanding Fuel Efficiency and How It Is Affected
1. Vehicle Efficiency
When manufacturers build cars, they spend a great deal of time focusing on the shape of the vehicles. In today’s world, people want to travel further, faster, and for less. These cars undergo rigorous testing in wind tunnels and on the road. The tests help to slimline the design, allowing the vehicles to slide through the air with ease.
A few things influence the adeptness of a vehicle to maintain a relatively low fuel economy.
- Your driving style is one of them. Tests show that driving a vehicle aggressively increases fuel consumption. By this, we mean accelerating car speed and then coming to a halt, then speeding off again. Manufacturers recommend going at a moderate pace to keep your gas mileage down.
- Tire pressure also plays a role in fuel economy. Under-inflated tires don’t run smoothly on the road. They lead to increased consumption of gas.
- Running your car’s air-conditioning will also lead to increased fuel use. So to save, ride with your windows down instead.
- Traveling at high speeds requires an extra force that leads to more gas being used up. The car speed for best mileage per gallon is moderate acceleration. This is crucial for areas where you need to stop at intersections.
- One of the largest impacts on fuel efficiency comes in the form of aerodynamics. Vehicle producers design their cars to be as sleek as possible. The lack of streamlining comes from the elements we add to our cars or the alterations we make to them. By increasing the suspension or adding roof racks, the vehicle’s drag increases. This results in a rise in the fuel used. It is then important to ask: what is a drag?
2. The Science of It All
Drag is the resistance of your vehicle when you travel in a direction. The more drag your car offers, the more power it needs to move in a forward or backward direction. Increased power means increased fuel consumption.
The resistance of your car increases as you change it. Adding roof racks to the top of your car does just that. Even only the racks or roof basket alone will reduce the aerodynamics of the vehicle. When you pile on luggage or items such as bicycles, this resistance increases tenfold.
Why do these items create drag? The answer is simple; much like the sail of a boat, your luggage catches the wind. Your car needs to push forward against this force to keep moving in the intended direction. By adding your surfboard or suitcases to the roof you affect the airflow. The air that would typically flow over your car has to find another route.
3. What Causes The Most Drag?
Tests carried out on cars without roof baskets show that they offer the best fuel efficiency. The same vehicles then had roof racks installed and were retested. The results showed that with a roof rack, gas mileage decreased. Even when they aren’t carrying luggage, these systems increase drag, costing you more to get from A to B.
When testers topped these roof racks with items, the change in gas mileage became clear. Unusually shaped items such as Kayaks had a modest effect. Still, it was luggage piled high and bicycles that created the most drag. Verticality creates more wind resistance than long items or those you can pack to lie close to the car’s roof.
4. Do Roof Racks, Roof Baskets, and Cargo Carriers Affect Drag?
Factory-installed roof rails run the length of your car, working with the roof’s sleek design. They provide little to no resistance as they run in the direction of the airflow. Roof racks usually come as two crossbars that sit horizontally across your vehicle. The positioning of these bars causes them to create wind resistance. This then increases your vehicle’s drag. These racks may not seem like much, but it is their positioning that poses the problem.
Roof baskets attach to roof racks. They take on the form of a metal basket-like structure that sees raised sides to keep goods contained. These holders often come with a wind deflector. This flap connects to the basket’s front, forcing the air to flow around it more easily. These deflectors work to a degree to streamline the roof baskets. However, the roof racks and luggage piled above the wind deflector change the vehicle's shape. This leads to an increase in the amount of gas needed to propel the car forward.
- Cargo Carriers
Cargo holders or roof boxes offer the sleekest design. Most of these see shapes that follow the vehicle's aerodynamics, lowering gas consumption. Because they contain your goods, they prevent irregular shapes from increasing drag. However, they do not prevent resistance. These roof boxes attach to the roof racks already installed, raising the carrier. The extra height, the drag of the racks, and the change to the car roof's shape will all lead to the amount of fuel needed.
Can Poor Gas Mileage Be Prevented?
Getting the best car mileage per gallon when you have roof racks attached to your car depends on a few things. By following these simple bits of advice, you can keep your fuel consumption low.
- Remove your roof racks when you aren’t using them. As discussed earlier, these systems add drag even when they don’t have goods attached to them. Installing them from your car will reduce your day-to-day gas consumption.
- Pack your roof racks so that your luggage stays more horizontal than vertical. Piling your bags or other goods into mountains on top of your car roof will cost more. Rather lay them flat and close to the vehicle. Making use of the right system for your needs will help with this.
- Don’t drive around with items such as kayaks or bicycles tethered to your roof racks. Unless you plan on using them on your adventures for that day. The bikes may look cool, but your fuel bill won’t be.
- If you are going on a vacation and intend on bringing various bulky goods, transport them in a cargo carrier. These boxes offer a more streamlined solution. They create less resistance than a collection of odd shapes.
- Use the right rack or carrier system for your needs. Attaching a huge cargo carrier to the car decreases your fuel efficiency. The larger the basket or roof box, the greater the surface area they offer, and the more drag they make. Here, less is more.
It is impossible to prevent increased fuel consumption when using a roof rack system. Staying aware of how these systems affect your gas mileage goes a long way. Following a few simple tips, you can prevent a huge gas bill. Take a look at some of the unique roof rack systems we have to offer, to find the system that best suits your needs and your vehicle.