Car-top cargo boxes are great for hauling gear, but they do decrease gas mileage by adding weight and wind drag. The Twistboxes carrier offers a partial solution to that problem, as it quickly comes off and rolls up when not in use.
Invented by Swedish outdoors enthusiast Mikael Nelderup, Twistboxes is currently the subject of a Kickstarter campaign.
The device consists of a flexible steel base plate with an upward-curved front end (like the front of a toboggan), which is encased within a padded 1680D PVC-coated ballistic nylon body. The latter material is fully waterproof and 50+ UV-protected, plus it incorporates waterproof zippers for accessing its 520 liters of internal cargo space.
Once in place, Twistboxes offers the form and function of a traditional hard-shell roof box, with the added benefits of weighing about half as much (about 22 kg/48.5 lb), not producing any whistling noises at high speeds, and reportedly being quite easy to remove when not needed. A set of tensioning bars make its base plate rigid while it's on the vehicle.
The whole rig can reportedly be taken off in less than one minute, then rolled up into a closet-storable cylindrical package with a diameter of 35 cm (13.8 in). By contrast, because conventional roof boxes are trickier to remove and much bulkier to store, they often just end up staying on the vehicle full-time.
Additionally, whereas traditional roof boxes can only be loaded via a lid on top, Twistboxes can also be loaded via zippered fold-down panels on the sides. What's more, those panels protect the car's roof as gear is going in and out.
As far as third-party rack compatibility goes, Twistboxes is claimed to be compatible with all rails, and it mounts in the same manner as other roof boxes utilizing included hardware. Road tests have shown that when loaded with 75 kg (165 lb) of gear, it remains securely attached even when the vehicle suddenly brakes from a speed of 80 km/h (50 mph).
Assuming everything works out, a pledge of €899 (about US$961) will get you a Twistboxes setup of your own – that's 50% off the planned retail price. There's more information in the following video.
Sources: Kickstarter, Twistboxes
