Katy Guest: My name is Katy, and I suffer from AGPS Jealousy Disorder

Figures are not yet in on how many couples have survived the long wet summer holidays together, but the latest publication from the Department for Spurious Statistics brings further cause for relief that the circus is over for another year. It will come as no surprise to anyone who drove to Cornwall/Ayrshire/Marrakesh with their (possibly former) beloved this summer, but researchers at Seat, the car manufacturers, have found that couples often argue on long car journeys. One in five has pulled over and told their partner to get out; 3.5 million relationships have ended following an in-car row; and the average driving time before the fireworks start is 22 minutes. It almost makes Ryanair look like the easier option. (I said almost)

The research showed that the most common causes of arguments were getting lost, lousy parking, driving too fast and backseat driving. It also found, curiously, that satnavs lead to more harmonious journeys. I am personally surprised that more couples don't split up because he sides with the disembodied voice of a frosty female robot over a human navigator and downright refuses to apologise when his girlfriend turns out to have been right all along, but perhaps it is possible that Anthropomorphic Global Positioning System Jealousy Disorder is not quite as widespread as I had allowed myself to believe.

The sad thing about these statistics is that it's pointless to argue with someone about their driving. Trust me: I have done research and I can tell you that there is no neutral, calm and helpful way to ask someone if they have any idea how fast they are driving, and that jamming your foot on an imaginary brake and invoking the sweet baby Jesus and his family members is probably not the best way to alert your driver to the presence of an obstacle to which he has apparently been oblivious heretofore. Likewise, when a person has just spotted that she's been in the wrong gear since Bradford, it is seldom useful to roll your eyes and reveal that you noticed it miles ago.

However, if we could just agree to keep our traps shut about each other's braking distance awareness issues and avant-garde overtaking manoeuvres, we would see that the car is really the best place to have an effective argument. In fact, it provides an environment that is spookily reminiscent of couples therapy.

For starters, neither party can escape if the atmosphere starts to become a little awkward: just try making for the door when you're sailing along the M4 at 90mph and someone decides to ask you just Exactly Where You Think This Relationship Is Going. And then you find that the facing forwards position makes for a much easier exchange of views: nobody can analyse your face for hidden meanings when they are concentrating on the road ahead, and it is unlikely that your passenger will thump you when their safety rests on your grip on the wheel. Each person can take turns to speak, and there's plenty of time to think about what's said. Ultimately, it's still the two of you against the traffic. And, whatever happens, it is essential to stay calm. You can't even burst into tears when seeing is so important.

But by far the best thing about the in-car bust-up is that it has a known and finite endpoint. You must come to terms by the time you reach your destination, smooth yourselves down, snog in the carpark and swan into the campsite/wedding/match feeling smugly united and grown-up.

Until, that is, the bitch SatNav pipes up and starts egging him on to "make a U-turn".