Good foundations matter, and if you’re planning to add a roof box or bike rack to your tow car when packing for caravan holidays, you’ll need decent roof bars. 

At first glance, you may not spot the differences between rival roof bars on the market for your car. Look closer and you’ll soon realise that small refinements in design can make a huge improvement in terms of wind noise, fuel consumption and so on. 

Load-bearing capacity varies quite a bit between brands as well. Make sure you know the maximum load that your tow car is capable of bearing as well as the roof bars’ upper limit. When you’re calculation the load you’ve put onto your car roof, don’t forget to include the weight of the roof bars themselves.

What look like the best roof bars in the world will soon drive you mad if they’re fiddly to fit, so in our group test of roof bars we’ve given higher marks to the products that are easy to fit. Some are vehicle-specific, while others are modular systems, designed to fit any car. Roof bars that have been designed for your car only tend to be easier to fit in place securely, but on the other hand if you sell the car and buy a different make and model, you’ll have to buy new roof bars for your new car. 

In these tests we’ve been weighing up the pros and cons of each set of roof bars, to make sure you buy the best. We have focused particularly on rail-fit bars, and where we can we’ve also tested the same bar fitted with mounts designed to be secured to door apertures.

The latter are more difficult to install, because they work as a whole. Ideally you need two people to fit these, because when you tighten the foot and clamp into one door aperture, it pulls against the foot and clamp on the other side of the car. So when you adjust one side you might end up with a foot too far over the roof’s edge, which will make it loose. With two of you, it’s easier to adjust both sides at once, little by little, until the bars are firmly attached.

Security aspects are also important when deciding which roof bars to buy. Some have anti-theft locks and T-tracks. These narrow grooves are cut into the top of premium bars and work by receiving special bolts to secure your load. T-track bolts are easier to fit than U-bolts, because they don’t have to be kept pressed against the bottom of the bar while being pressed from above.

In our test, all rail-mounted roof bars were ordered for the Volvo V70/850 Estate.

Here we are testing the Auto Maxi Activa Steel 125, which costs £145.10. The stickers may say AutoMaxi, but the firm has been absorbed into Mont Blanc for some time now. So, other than the bars being square, steel, and cheaper, there’s not much to choose between them and the Mont Blanc 1250 Activa Alu roof bars.

Naturally, 100kg max loading from a steel bar means these are pretty heavy — though not as bad as the 12kg Atera Signo. And, predictably enough, the square profile creates more wind noise when unloaded.

But in all other ways, these bars and their aluminium siblings are the same. Both have five-year warranties, both come ready to fit, and both have the same foot-cover plates that double up as Allen keys, making fitment fast, easy, and with no need for additional tools