The Most Efficient Roof Top Cargo Box

One of the most useful car add-on's I've used in recent years is the rooftop cargo box. I've owned several different models including Thule and Yakima and enjoyed the latest and greatest features such as dual side opening and easy install. Roof top cargo boxes are especially useful for skiing and camping trips where car space is limited, especially if you don't have a station wagon or SUV. The disadvantage and drawback to any cargo box is however, that it creates increased drag on your vehicle which decreases gas mileage and overall vehicle efficiency. This drag isn't nearly as bad as a bicycle or ski rack with gear in tow but most people take off ski and bike racks when they aren't in use vs. cargo boxes that are left on year round.

In my search for the perfect cargo box, efficiency and aerodynamics has been a leading factor. Depending on car design, a long thin box like the one shown above is usually the best choice. This approach fails however if the car is short and the box hangs way over the windshield; not only does this create drag it also creates a safety hazard.

An alternative to finding the most efficient box design and leaving it on permanently is choosing one that is easy to put on and take off, and more adept for storing. With this method you just take the box off when it isn't in use (for me 90% of the time going to and from work etc.) but this creates a storage issue. Not only are these boxes large, usually requiring two people to remove without the risk of injury or damage to the car or box, they are also awkward to store. At one point I was storing my silver Thule Atlantis in a crowded garage space when a friend's bike fell on it and created a large scratch across the top. Just two weeks later the garage ceiling collapsed and deformed the top of the box even more.

Unfortunately, even if you avoid the pitfalls of storage and leave your cargo box on top of your car 100% of the time (where it is presumably safe from dings and scratches) the sun is going to fade the paint and tree sap and other debris will eventually build up. You also have to deal with the added risk of physical contact with low hanging pipes, garage doors and drive through stations... Here in San Francisco there are plenty of very low clearance parking garages that could wreak havoc on a thin plastic box, your car's roof and your pocketbook.

So what's the solution here? Well, there is one category of rooftop cargo boxes that I haven't mentioned in this overview so far and it's the one that is most efficient in my mind. Not only is it easy to remove, it is easy to store and therefore won't bog down your MPG's or your pocketbook because it won't get damaged as easily. It isn't quite as pretty to look at and it will probably create more drag than the aforementioned hard shell boxes, but for those only looking for occasional roof storage it's a great compromise.

I'm referring of course, to rooftop cargo bags. These alternative rooftop storage devices were first made popular by a little company called RoofBag in 1992. Since then, both Thule and Yakima have created similar products but RoofBag remains the leader and innovator. A roof bag works much like a cargo box but is made out of flexible waterproof rubber and fabric that is much easier to fold up and store. The great part is, you can use a roof bag whether your car has cargo rails and crossbars or not. This is great news for hybrid and electric vehicle owners because most of these vehicles don't come stock with racks. I found it especially hard, for example, to find crossbars for the first generation Honda Insight (2000-2006) but a RoofBag would still work for this car.

For under $100 you can get a RoofBag and end up saving a ton of gas, effort and money in the long run. Depending on your specific needs, length might be an issue but this can be overcome with a little creative thinking. Most sedans, for example, have a pass through door to the trunk so skis or snowboards could fit inside while other gear is put up top.

Most roof bags are lockable and no matter which brand you get there are several accessories worth considering. RoofBag offers a tire step for reaching the top of your roof more easily, duffel bags for organizing your stuff inside, a storage pouch, extra straps and a protective mat to keep the top of your car in good shape.