By the time you read this, testing for the Tow Car Awards 2015 will have started. As I write, tyre pressures are being checked, tow balls fitted and caravans ballasted, ready for the tests to begin in earnest.

The awards are now in their ninth year. By the time 2015’s tests have finished we’ll be hovering around 400 cars tested.

This year promises to be one of the best yet. For one thing, the sun is shining (pumping up dozens and dozens of car and caravan tyres in the rain is not fun). For another, we’ve got a strong line up of shiny new models to assess, to determine what tow car ability they have.

Some nearly didn’t make it all. Two days before the test preparations began, Ford told us it wasn’t able to send any Mondeos because towing gear for the car was on back-order. But at the eleventh hour the parts arrived, were fitted, and we now have a petrol and a diesel parked and ready to go.

The Mondeo has some tough competition. The new Volkswagen Passat is roomier, better finished and more economical than before. We’ve got the best-selling diesel to test, and the powerful four-wheel-drive version.

Land Rover usually does well in our tests. Among Land Rover’s entrants in this year’s competition is the new Discovery Sport. With seven seats rather than five, the Discovery Sport is more practical than the Freelander it replaces. The 2.2-litre diesel engine may be getting on a bit, but it has more than enough muscle to comfortably tow a mid-sized tourer.

The Kia Sorento is an ever-popular car with caravanners, although it’s the first generation which is probably best loved. The new car continues Kia’s push up market, and it will be fascinating to see if the latest model justifies its higher price. The Sorento is certainly well equipped, heavy enough to make a suitable match for a big twin-axle caravan, and the brawny 2.2 diesel should have the punch to cope.

We have some intriguing smaller tow cars on test, too, not least the new Suzuki Vitara. With a tiny kerbweight of 1295kg, it has to be one of the lightest 4x4s on sale. That means it’s only suitable for small and light tourers if you follow the 85% guideline, but if you own a small tourer or micro-caravan and like to stay in out-of-the-way places, the Vitara has to be one to watch.

Nissan took the big prize last year, and the Qashqai is back to defend its crown. It’s supported by the Pulsar, Nissan’s new Ford Focus rival, and the X-Trail SUV. Like the Discovery Sport, the X-Trail now offers seven seats (five-seat versions are available, too), but at a much lower price than you’d be charged in a Land Rover showroom.

Every car will go through the same rigorous and demanding tests. We measure 30-60mph acceleration to gauge overtaking ability and the strength of the engine in pulling an outfit up to the legal limit. We like our cars to stop as well as go, so each combination performs a 30-0mph braking test.

We drive at speeds beyond what’s legal on UK motorways, so we can sort the great from the merely very good. Each car also takes on a hill start on a 1-in-6 slope: it’s surprising how many handbrakes struggle to hold outfits on this gradient.

Perhaps the toughest test is the lane-change manoeuvre. Cars tackle the course three times at steadily increasing speeds. It’s far more violent than anything you would tackle on the public road unless faced with an emergency, but we want to know which cars will help a driver retain control in extreme situations – and hopefully avoid an accident.

The driving assessment is just one part of the testing. Our friends from The Camping and Caravanning Club assess each vehicle’s practicality as a tow car, looking at boot space, the spare wheel provision, the ease with which towing mirrors can be fitted and even little details such as whether there is a 12v socket in the boot.

Each car is also scored in day to day driving by our colleagues on What Car?. After all, unless you have the luxury of owning a car just to tow with, you’ll want to know what it’s like to drive everyday, as well as when caravanning.

What Car? also scores each car for ‘Buying and owning’, which covers safety, value, running costs and future resale values. We don’t want to recommend cars which are great to tow with but which prove a nightmare to own in the long run.

So, that’s how we look for Britain’s best tow cars each year. We should know the answers by the end of next week. The winners will be announced in mid-June.