HAMBURG: Anyone who wants to transport luggage on the roof of a car needs to know a few things. Attachments such as a roof box change both the weight and the centre of gravity of the vehicle - and thus also the handling.
What's more, a car with a roof box will react more sensitively to crosswinds. That's why you'll need to stay more alert, especially on bridges, in narrow forest roads or when overtaking lorries.
Most countries don't have set limits on driving with a roof box, but this is different for manufacturers, and most will advise you don't break the 130kph mark. A maximum speed specified by the manufacturer of the box should not be exceeded under any circumstances.
"Before buying, shoppers should first have a look at their car’s user manual," suggests Philipp Schreiber, a vehicle tester.
The manual will indicate whether the car has been approved for a roof load in the first place and, if so, how heavy it can be. In general, roof-load ratings range from 50kg to 100kg total.
"With the exception of convertibles, most cars can have a roof box installed," says Schreiber. Once you’ve decided on a size, shape and capacity, the next step is to figure out how the roof box will be mounted and fastened to the vehicle.
"There are various options for mounting the roof box, since the manufacturer may have provided the car with front-to-back rails on its roof, or gutters or so-called fixpoints," explains another tester, Thomas Caasmann.
While most modern-day cars come with the manufacturer-installed fixpoints, which are usually hidden under flaps or sliders, it’s not always a guarantee that the chosen model of roof box will line up with the installation points on a car’s roof.
The most convenient mounting systems are the ones with quick-release fasteners, since they allow for quicker and easier installation without having to worry about screws, nuts and hooks.
Another thing to consider before buying a fixed roof box is which side it opens - to the left, to the right or from both sides.
As Caasmann notes, "A lid that can open on either side always offers better access to the storage space."
"For trips, it’s also important to consider theft protection for the contents of the roof box, as well as its water resistance in case of rain or heavy spray," adds Caasmann. Some manufacturers offer specially integrated locks.
Carsten Graf of car club ADAC recommends a systematic approach to packing a roof rack before heading off on a road trip.
"When loading, the same principles apply as when packing items into the trunk: heavy things on the bottom, lighter things on top."
Bags, sleeping bags or blankets should all go in the front section of the box, since, as Graf points out, "this reduces the danger of pointy objects breaking through the box in an accident."
For the same reason, all luggage should be kept in place with straps.
"Roof boxes should also never be overloaded," adds Graf, "so you should always keep in mind the car’s maximum roof load." The load should be calculated by adding up the weight of the items in the box, the box itself and any roof bars.
A good roof box doesn’t have to be expensive. The ADAC, which is a German organisation, tested models between €200 and €700 (between RM1,007 and RM3,525), with the winning model coming in at €408 (RM2,054).
After being used on a trip, a roof box should find its way back into the garage or basement since it creates wind resistance and increases fuel consumption if driven around empty.
