When you’re packing for your caravan holidays, whether you load a roof box or a bike rack on top of your tow car, you have to start with a good pair of roof bars. While these have been around for years, there’s never been more variety than now.

For example, they have different shapes to reduce wind noise and drag, which improves fuel efficiency, compared to traditional square-section bars.

In addition, different models can support different maximum loads. Avoid exceeding the lower of your vehicle’s maximum roof load weights – including the weight of the bars themselves – or the bars’ maximum.

Then the roof bars must be fitted; that’s easy with one that’s vehicle-specific. It’s not the case with modular systems, but then these can be used on any type of car.

Bearing all this in mind and to help you make the right choice before you head off on tour, we’ve brought a collection of roof bars together to review, to help you buy the best.

In this test, we’ve concentrated on rail-fit bars. Where possible, we’ve also evaluated the same bar fitted with mounts designed to be secured to door apertures.

The latter are more fiddly to install, because they work as a whole. When you tighten the foot and clamp into one door aperture, it pulls against the foot and clamp on the other side of the vehicle. If one adjustment brings a foot too far over the roof’s edge, loosening that foot and pushing it slightly further down the bar may necessitate adjusting the other end. So get someone to help with the job.

Other features to look for when considering what roof bar to buy are locks to deter thieves and T-tracks, which are narrow grooves cut into the top of premium bars that receive special bolts to secure your load. Unlike U-bolts, T-track bolts don’t have to be kept pressed against the bottom of the bar while being pressed from above.

In this test, all rail-mounted bars were ordered for Volvo’s venerable V70/850 Estate.

Here we are testing the Thule WingBar, which retails for £150.50. Nobody’s mastered the concept of modular roof bars like Thule. Its range of applications is massive, its brilliant designs make assembling bars to feet and, with door-aperture models, bars to feet to retaining clips fast and simple, with no need for tools.

Fitting is easy: unlock a small piece of trim, pull it out slightly and it becomes a lever. Rotating it secures or loosens the foot’s jaws around the roof rail as well as the foot’s position along the bar.

WingBars are Thule’s latest aluminium roof bar, with a noise-reducing and fuel-saving aerofoil shape, a 100kg maximum load, a T-track, and a five-year warranty. And all for less than most premium bars!

And, come the end of the Practical Caravan roof bar group test, the Thule WingBar emerged as the winner, receiving a five-star rating. We also reviewed the Mont Blanc Supra 004.