Cars don't rust any more, well that's what i keep reading, its all rubbish of course under the shiny bits of plastic they can still rust quite adequately.

Whether a claim would be successful depends on the terms of warranty, and i have no doubt part of that would be a full and complete service history and an annual inspection by the main dealer of bodywork, then its the degree of rusting, perforation being the usual caveat, if you have a fully stamped service history, including body inspection by the mian dealer and the body warranty is still valid then i see now reason why the claim should be rejected..unless the car has had any other body reapirs not up to Nissan bodyshop standards, whatever they might be.

Yes the car has a full Nissan service history and has had its annual bodywork inspections each year.Dealer has confirmed that it has a 12 year anti corrosion warranty but my car has failed on their " screwdriver test" this they tell me is where a screwdriver can be pushed through the bodywork. After contacting two other independent body shops they tell me it's a common problem with Xtrails as water under the wheel arches penetrate between the two skins causing rust. But it's convincing Nissan that there is clearly a problem with the seal.

The car does NOT have a 12 year 'anti-corrosion' warranty. It HAD a 6 year 'anti-corrosion' warranty, and a 12 year 'anti-perforation' warranty.

Corrosion is minor surface rust - which is what you have.

Perforation is the panel rusting through completely - which is what the screwdriver test checks for. If the screwdriver can be pushed through with only a minor amount of force, then the rust has eaten all the way through.

There is a major difference between corrosion and perforation.

Just had a quick browse on t'web.

It appears that Nissan's corrosion warranty for the X trail of that age was a 6 year anti-corrosion warranty, and a 12 year anti-perforation warranty.

"beginning to rust" is corrosion, for which the warranty ran out 5 years ago.

Now, in case you were thinking of leaving it for a year to see if it got worse (and then trying to claim on perforation warranty), do be aware that these really long rust warranties usually require the car to be inspected by a main agent dealership annually, and for ANY damage or rust to be rectified promptly.

So, has the car been in to Nissan EVERY year from new for a corrosion inspection, and has that been logged in the service handbook ?

Because if not, then you haven't got a hope. Even if it has, then you STILL haven't got a hope, because it hasn't perforated, only corroded. And that warranty ran out 5 years ago.