What are the benefits of extra luggage space outside the car?
29 July 2026
Extra luggage space outside the car literally gives you more freedom on vacation. By mounting a roof box on your car, you add hundreds of liters of cargo space without having to compromise on legroom or passenger comfort inside. For families traveling by car, this is one of the best investments you can make. In this article, we answer the most frequently asked questions about roof boxes, from space and safety to fuel consumption and the choice for your family.
How much extra space does a roof box give you?
A roof box typically gives you between 300 and 600 liters of extra luggage space on top of your existing trunk. In practice, this is enough for multiple suitcases, ski bags, child seats, or camping equipment that simply wouldn't fit otherwise. The exact gain depends on the model you choose.
For comparison: an average family car has a trunk of about 400 to 500 liters. With a 500-liter roof box, you effectively double your loading capacity. That makes a huge difference when you go on vacation with two children, a stroller, skis, and beach chairs. You don't have to leave anything at home, and the mood in the car remains good because there are no arguments about who gets to bring what.
Our Hapro roof boxes range from the compact Roady with 300 liters for the conscious traveler to the spacious Traxer, which goes up to 530 liters. This way, you will always find a size that suits your car and your travel needs.
What can you take with you in a roof box on vacation?
In a roof box, you can carry virtually all the luggage you would normally cram into the trunk: suitcases, bags, sleeping bags, ski clothing, camping gear, and sporting goods. It is ideal for lightweight but bulky items that take up a lot of space but weigh little, such as duvets, boots, and jackets.
There are, however, a few practical rules of thumb. Heavy items belong in the trunk, not on the roof, due to the car's center of gravity. Moisture-sensitive items such as electronics or papers can be safely transported provided the case closes properly, which is always the case with a TÜV-certified roof box. Also consider ski poles, snowboards, or surfboards: there are special ski carriers available for these that you can use alongside or in combination with a roof box.
A handy tip for families: use the roof box for items you don't need on the road, such as winter clothing, bed linen, or beach chairs. This way, the trunk remains free for the luggage you need first upon arrival.
Is a roof box safe on the highway?
Yes, a high-quality roof box is completely safe on the highway, provided it is mounted correctly and is not overloaded. Good roof boxes are tested for crash resistance, stability, vibrations, wind, and water. When purchasing, always look for TÜV certification, as this is proof that the box meets strict European safety requirements.
All Hapro roof boxes are TÜV-certified and thoroughly tested on all these factors. Installation is tool-free via our patented Premium-Fit mounting system, ensuring the box sits securely and reliably on the roof racks. Before departure, always check that the box is properly locked and that the maximum roof rack weight for your car is not exceeded. This weight is stated in your car's owner's manual and typically varies between 50 and 100 kilograms, including the box itself.
At high speeds, a aero dynamic design is also important for stability. A well-shaped roof box cuts through the air rather than working against it, which is not only safer but also improves driving comfort.
How much fuel does a roof box consume?
A roof box increases fuel consumption by an average of five to ten percent, depending on driving speed, the weight of the load, and the aerodynamics of the box. The effect is greatest at higher speeds on the highway, because air resistance increases exponentially with speed.
The impact can be limited by making a few slimme choices. Opt for a dynamically shaped roof box instead of a wide, flat variant. Do not load the box heavier than necessary and remove it when not in use, as even an empty roof box increases drag. Drive a little slower on the highway, because driving at 110 kilometers per hour instead of 130 makes a noticeable difference to your refueling.
In practice, the extra fuel consumption for a family trip to the South of France or Italy means limited additional costs. Compare that to the convenience and comfort you get in return, and the net result turns out to be significantly better for most families.
What is the difference between a roof box and a roof tent?
A roof box is a hard, closed storage box on the roof of your car, intended for transporting luggage. A roof tent is a foldable tent that is attached to the roof of the car and serves as a sleeping place during camping trips. They therefore serve a fundamentally different purpose: storage versus overnight stay.
The choice between the two depends entirely on your plans. Are you going on a classic holiday to a hotel or apartment and do you simply need more luggage space? Then a roof box is the logical choice. Do you want the freedom to spend the night anywhere, directly from your car, without setting up a tent? Then a roof tent is an adventurous and comfortable option.
Some campers combine both: they use a smaller roof box for camping gear and drive with a roof tent as a sleeping place. This does require a sturdy roof rack system that can support the weight of both. Always check your car's maximum roof weight before combining these.
When is a roof box the best choice for a family?
A roof box is the best choice for a family when the trunk is structurally too small for all holiday luggage, but you still want to drive in the comfort of an enclosed car. This is the case for virtually every family holiday with young children, where strollers, child seats, toys, and multi-season clothing need to be brought along.
Specifically, a roof box is ideal in these situations:
- You are going on a winter sports holiday with the family and have brought skis, ski boots, and winter clothing.
- You drive to the campsite or the beach and have chairs, parasols, and toys with you.
- You are traveling with multiple children and want everyone to sit comfortably without suitcases on their laps.
- You are taking a longer car trip where you do not want to stop to rearrange luggage.
- You want to keep the trunk clear for items you need quickly on the road.
A roof box is also a slimme long-term investment. You buy it once and use it for years, for every holiday. With the online configurator On our website, you can quickly check which roof box and roof rack fit your car perfectly, so you can be sure you are making the right choice for your family and your travel plans in 2026 and beyond.
Frequently Asked Questions
How do I know which roof box fits my specific car?
Most roof boxes can be universally mounted on standard roof racks, but the correct size depends on the width of your roof racks and the maximum roof weight of your car. Check your car's owner's manual for the permitted roof weight, and then use an online configurator — such as the one from Hapro — to see exactly which roof rack and roof box combination fits your car make and model. This way, you avoid buying a box that is too wide, too long, or too heavy for your roof.
What are the most common mistakes when mounting a roof box?
The most common mistake is not locking the roof box properly before departure, which can cause it to vibrate while driving or, in the worst case, come loose. Another common mistake is overloading the box or distributing the weight unevenly, which negatively affects handling. Also ensure that the box always rests on the roof racks on both sides and check after the first ten kilometers of driving that everything is still securely fastened — especially with a newly mounted box.
Can I also use a roof box if I don't have roof rails on my car?
Yes, that is possible, but you will first need separate roof racks that attach via the door trims or the door frame edge of your car — also known as 'clamp-on carriers'. These are available for almost every car model and form the base on which you then mount the roof box. Do make sure that when purchasing roof racks, you choose a set that is specifically suitable for your car so that the attachment is secure and stable.
How do I maintain my roof box so that it lasts for years?
Clean the roof box after each use with lukewarm water and a soft cloth to remove salt, dirt, and insects — especially after a beach or winter sports holiday. Lubricate the locks and hinges with silicone spray one to two times a year to keep them smooth and prevent rust formation. Preferably store the box indoors or in the garage when not in use, and never leave it standing for extended periods with moisture inside the seals, as this can damage the seal.
Do I need to inform my insurer if I mount a roof box on my car?
In most cases, you do not need to report a roof box separately to your insurer, as it is a temporary and removable accessory. However, it is wise to check this with your own insurer, as some policies have specific conditions regarding roof loading or accessories above a certain value. Also, inquire whether the contents of the roof box are covered under your travel insurance or contents insurance in the event of theft or damage while traveling.
Is a roof box also suitable for use in winter and bad weather?
Yes, a TÜV-certified roof box is fully weather-resistant and designed to function even in rain, snow, and freezing temperatures. The seal ensures that the contents remain dry, and the construction withstands the extra load of wind and cold on the highway. However, please keep in mind that in case of snow or ice, you must thoroughly clear the car roof and the top of the roof box before departure, for both your own safety and that of other road users.
Can I rent a roof box instead of buying one if I only use it a few times a year?
Yes, roof box rental is a viable option if you only need the box once or twice a year and do not want to incur the purchase costs. Many camping stores, car rental companies, and specialized online shops offer roof boxes for rental periods of a week or longer. However, keep in mind that if you use the box three or more times a year, buying will be more cost-effective in the long run — and you also always have the assurance that the box will be available when you go on vacation.