The presence of a roof box perched atop a vehicle often evokes the exhilaration of road trips and the freedom of wide-open spaces. Yet, when the journey concludes and the routine of everyday life resumes, the question emerges – should the roof box remain on the car? This seemingly simple question opens a Pandora’s box of considerations, ranging from the design and durability of roof boxes to their impact on vehicle performance and practical concerns.
Roof Boxes: A Testament to Robust Design
Roof boxes are a testament to meticulous and robust design, marrying functionality with durability. They are crafted to endure the challenges of both weather and road conditions, making them an indispensable accessory for road trips, family outings, and outdoor adventures.
At the heart of the design process, the manufacturers put a keen emphasis on material selection, primarily utilizing ABS (Acrylonitrile Butadiene Styrene) plastic or carbon fiber. Both materials have been chosen for their exceptional strength and ability to withstand the elements.
In general, there are two types of roof boxes readily available on the market: ABS and fiberglass reinforced polyester (fiberglass for short). Fiberglass is significantly more robust and durable than ABS.
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ABS plastic, a common material in the production of roof boxes, is revered for its toughness and impact resistance. It boasts a remarkable ability to maintain its shape and structural integrity, even in the face of extreme temperatures – from scorching summer heat to frigid winter cold. Its resistance to corrosive substances also ensures that it can stand up to the wear and tear of road salt and other chemicals that it may encounter during its lifetime.
On the other hand, carbon fiber represents the premium end of the roof box spectrum. Known for its superior strength-to-weight ratio, carbon fiber is both lightweight and incredibly strong. This makes carbon fiber roof boxes an excellent choice for those who demand top-tier performance without compromising on fuel efficiency. Moreover, it is inherently resistant to UV rays, thereby reducing the risk of the box becoming brittle or fading over time.
In addition to the material, the structural design of the roof boxes also plays a crucial role in their robustness. These boxes are crafted with aerodynamics in mind, featuring a streamlined shape that reduces wind resistance and noise during travel. This efficient design not only enhances fuel economy but also contributes to the overall stability of the roof box, even when driving at high speeds or in adverse weather conditions.
The Aerodynamic Equation and Fuel Efficiency
The robust architecture of roof boxes, while impressive, only paints part of the picture. The way a vehicle interacts with the air around it – its aerodynamics – significantly changes when a roof box is added. This addition introduces an element that isn’t inherently aerodynamic into the vehicle’s overall profile, increasing drag, which is a resistive force that works in opposition to the motion of the vehicle.
Drag is a key player in the aerodynamic equation. It’s the result of air resistance and the shape of an object moving through the atmosphere. When a roof box is added to a vehicle, it changes the shape of the vehicle and creates more surface area for the air to act upon. Consequently, the vehicle experiences an increase in drag.
The impact of this increase in drag is seen most clearly in a vehicle’s fuel efficiency. To combat the additional resistance introduced by the roof box, the vehicle’s engine has to work harder to maintain speed. This increased demand on the engine translates to more fuel consumption. While this effect might seem negligible during infrequent use, over time and especially with the roof box as a permanent fixture, it can lead to significant additional costs.
For example, if a vehicle’s fuel efficiency drops by even 2% due to the increased drag from a roof box, this could add up to hundreds of dollars in extra fuel costs per year, depending on how much you drive.
The empty roof rack had a nearly 2 percent impact on fuel economy, which translates to a little more than three-quarters of a gallon of gas.
https://www.consumerreports.org/fuel-economy-efficiency/how-rooftop-carriers-affect-fuel-economy/
This effectually undermines the economic efficiency of the vehicle, offsetting some of the benefits of having the additional storage space provided by the roof box.
However, it’s worth noting that the impact on fuel efficiency isn’t the same for all roof boxes or vehicles. Factors such as the size and shape of the roof box, the speed at which the vehicle is typically driven, and the original aerodynamic design of the vehicle all play a role. Manufacturers are aware of this issue and work to design roof boxes that are as aerodynamic as possible to minimize the impact on fuel efficiency. For instance, modern roof boxes often have a streamlined design that reduces air resistance and helps keep the increase in fuel consumption to a minimum.
The Elements and the Law of Unintended Consequences
Beyond the realm of aerodynamics and fuel efficiency, leaving a roof box mounted indefinitely exposes it to potential hazards. For instance, the ultraviolet (UV) radiation in sunlight can induce UV damage, a form of degradation that can result in discoloration and weakening of the roof box material over time.
Roof boxes are generally made from pigmented polyester (known commonly as gelcoat) and as the surface suffers exposure to UV rays (especially during the summer) the color and shine can both begin to fade and dull.
https://www.owatrolusa.com/automobile/how-to-stop-your-roof-box-from-fading/
Furthermore, the roof box could be vulnerable to damage from inclement weather, such as hailstorms or heavy snowfall, which could cause structural damage. Aside from the elements, the roof box could become an attractive target for larceny. While most roof boxes are equipped with locks, a permanently mounted roof box could pique the interest of opportunistic thieves, who might perceive it as a treasure chest of valuable items.
Practical Considerations in the Urban Jungle
The potential issues associated with leaving a roof box mounted on a vehicle are not confined to aerodynamics, fuel efficiency, or potential damage. Practical considerations can also throw a spanner in the works. For instance, the extra height due to a roof box could prevent access to areas with low clearance, such as parking garages or drive-thru services.
Additionally, the mounted roof box could complicate routine vehicle maintenance or inspections. Removal and remounting of the roof box could become a recurring nuisance, adding to the time and effort required for vehicle upkeep.
The Care and Keeping of Roof Boxes
Assuming one chooses to keep the roof box mounted indefinitely, a proactive approach to roof box care and maintenance can help mitigate potential issues. Regularly inspecting the roof box for signs of wear and tear, cleaning it to prevent the accumulation of grime, and ensuring it is securely locked when not in use can prolong its lifespan and maintain its functionality.
Tracking your vehicle’s fuel consumption can also provide valuable insights into the impact of the roof box on your vehicle’s performance and help you weigh the cost versus convenience of having the roof box ready for use at all times.
Conclusion
In the final analysis, the decision to leave a roof box on a car when not in use is dictated by a mosaic of factors that extend beyond the mere durability of the roof box. The potential impact on vehicle performance, the vulnerabilities introduced by prolonged exposure to environmental conditions and potential malefactors, and practical considerations related to everyday vehicle usage all add layers of complexity to this decision.
While it may seem convenient to always have extra storage space available, the trade-off comes in the form of increased fuel consumption, a potential increase in wear and tear, and the potential for theft. Conversely, removing the roof box when not in use may seem inconvenient, but this choice may also extend the lifespan of the box, improve vehicle performance, and provide peace of mind.
