EDIT Fall 2021:
Once it became clear that the56° Nord roof boxwouldnotbe comingonto the market, we decided to design our own our own roof box. This box would alsobe able to withstandhigher speeds and would have a strongfocus on aerodynamics and design. And after two years of development, we have finally achieved this: the development of aroof box for sports cars. Built for coupes, Avants, station wagons, and SUVs.
We are delighted to announce that you cannoworder ourASPHALTKIND roof box . . The first generation will be delivered in the fourth quarter of 2022 andwillinitiallybelimited to100 units. So be quick, because the first roof boxes have already been pre-ordered.
We tested various roof boxes for over a year. We weren't really satisfied with any of them, as individual features were often good, but the overall package left room for improvement.
Our criteria were attractive design, low weight, approval for speeds above 130 km/h, and pleasant wind noise.
We had already published several blog posts on this topic, but they have since been moved to the archive. Nevertheless, we would like to share the results with you in this short article and raise awareness of the issue to save you a lot of research work.
Appearance in photos differs from reality
The first thing we noticed was the edited photos and illustrations used to make the roof boxes look as harmonious as possible with the vehicles. This means that the boxes always look really good—until you see them on your own car, which may not have been modified.
Roof box design vs. automotive design
Many roof boxes are designed by designers who are opposed to current automotive design or who are unfamiliar with automotive design.
As a result, many boxes feature pronounced ridges and edges, which were last seen in automotive design in the early 2000s.
However, in our opinion, a clean and tidy design is currently more appropriate. Without tunnels, beads, edges, spoilers, etc.
Based on our own experience in development, clean design is considerably more challenging, as every line must be just right.
Basically, a roof box should not look like a foreign object on the car. This is really not easy, but it is doable!
Proximity to the car
In line with the previous point, the boxes always appear very close to the car in photos. It simply looks sportier. However, if they are also very close to the car in reality, this can even lead to problems. We always wanted to have our test boxes as close to the car as possible and tested various base carriers. Visually, it does indeed look a little sportier. However, there are two fundamental disadvantages: the box hits the car roof when it is loaded or "swings" when empty. This causes many small scratches.
The box is too close to the car, causing scratches and impairing aerodynamics.
Another problem we noticed is aerodynamics: there is air congestion in front of the box and no wind passes under the box. This becomes apparent when you don't have a rear windshield wiper and are dependent on the airflow. This would be manageable if it weren't for the rear spoiler and the car's own aerodynamics: when there is no longer any airflow at the rear of the car, the cars experience aerodynamic problems in terms of downforce.
We also spoke to a development engineer at Porsche on the phone, who confirmed that this is one of the reasons why care is taken to ensure that there is always enough airflow between the box and the car. Performance takes precedence over design.
However, our approach enabled us to resolve the conflict of objectives. We deliberately designed the lines to "move away from the car" in order to ensure perfect aerodynamics while still achieving a really good overall design for the car and pit box.
Roof boxes are designed to be opened
As silly as it sounds, one of the key features of roof boxes currently only works very rarely: easy opening and closing. The rather small key often has to be maneuvered into the keyhole first. After that, most models require quite a bit of force to move the inner rail, which meant that we were worried about stowing luggage in the roof box during a winter trip because we thought there was too great a risk of the key breaking off.
Apart from that, once unlocked, the biggest drawback for us with almost every roof box begins: opening the upper half. Due to the material and design, the upper half begins to warp. The hinges that allow it to be opened on both sides seem overwhelmed, and basically everything is just very wobbly.
We believe that a roof box should be as easy to open as a trunk lid.
The background noise
Admittedly, a Porsche 911 chassis and the lightweight insulation reveal almost every noise made by products located in or on the car.
This is also the case with roof boxes. As a result, almost all boxes rattled audibly at low speeds and made quite loud wind noises on the highway.
This would be acceptable for a low-budget product. However, we tested some rather high-priced speakers and find that there is definitely room for improvement here.
The weight should not be underestimated.
The first thing people often compare is the weight of a roof box. This is really important for the following reasons:
- you can load more
Some models require a roof box lift or several people (image source: ATU)
- The usual roof load is 75 kg, and if the box plus base rack already weighs 35 kg, there is less payload capacity left.
- the high center of gravity on the car is reduced
- When it is loaded, the center of gravity is negligible anyway, but you often drive with an empty box and learn to appreciate a light box on the car.
- The total weight of the car is reduced with a lightweight box.
- Anyone who wants to save fuel or energy, enjoys the dynamic advantages of the car, and also wants to stop quickly when braking, attaches great importance to the car having a low total weight.
- Often underestimated: installing and removing the box
- There were some test boxes that could only be carried by two people. This meant that there were times when the box was moved around unnecessarily because it could not be removed by one person alone.
The topic of speed
How fast can you actually drive with a roof box? Exactly. 130 km/h. For virtually every model we know, the manufacturer recommends 130 km/h. Often, it is stated that "you could go faster." However, in the event of an accident, the manufacturer will refer to the 130 km/h limit and thus avoid liability.
But the topic was also important to us for another reason: a 911 simply doesn't like to drive at 130 km/h all the time.
A comfortable cruising speed, which is easily achievable on some sections of the highway, is 170 km/h. This is also reflected in the feedback we received from BMW, Audi, Mercedes, and Volkswagen drivers: "We want to drive faster when traffic conditions allow."
A general speed limit for Germany has already been discussed, but here we see the idea of "If I wanted to, I could" in the foreground. As is generally the case with driving, the idea that you can actually drive anywhere at any time is not restricted by speed. Just as sports cars are sold in Switzerland despite the very strict speed limits there, roof boxes should not restrict your own car too much, at least in part, and should reflect the idea of freedom.
We received an apt comment in response to a query on our blog at the time, which sums up driving with a normal roof box perfectly: "The moment I put a roof box on my car, my Audi A6 turns into a truck. Slow, unaerodynamic, unstable, and unattractive. Just the thought that I can't drive faster than 130 km/h bothers me."
Speeds of up to 300 km/h, as experienced with a carbon fiber prototype, are actually possible. However, this has a negative impact on the overall weight of the box, as stability and weight often conflict with each other.
For us, it's important to have the right mix. The main focus of our roof box is not to drive at 300 km/h. Rather, it should be able to withstand a lap on the Nordschleife, where high (lateral) dynamic values are important, caused by tight, fast corners and heavy acceleration and braking. On the Döttinger Höhe (long straight), you could then put the box to the test in terms of top speed.
Summary
We really tested everything and were open to all manufacturers and promises. But we were never really convinced. So, where there's a problem, a solution should be worked on. We took this on board and are developing the perfect roof box for some people. Because the ones that already exist are by no means bad, but there's always room for improvement if you don't want to compromise.