On a boiling hot summer’s day everyone fantasises about getting the roof down on a convertible car and going somewhere with the wind in their hair. But the reality is that after five minutes everyone is looking for somewhere to pull over and put it back up again.

When you’re going quickly all convertibles, including those with aerodynamically tested wind deflectors behind the front seats, can turn even the sturdiest hairstyle into what appears to be a hurricane-ravaged stork’s nest.

The noise isn’t much good, either. Not that this will be much of a bother after 50 miles or so, because by then your ears will have filled with blood.

To make matters worse, you can’t drive a convertible car slowly either, because then people can see you. And what do you suppose they think? “Ooh, there’s a handsome and eligible chap.” Or “Ooh, look. That idiot’s burnt his bald patch. Small wonder his wife left him.”

If you have a convertible, you need to drive at a medium speed which a) means they do wonders for road safety and b) means you need pay no attention at all to the handling characteristics or power output.

Anyone who buys a 911 cabrio or a drop head Ferrari is a fool and a madman. Because what you’re doing is buying a car that may well be as much fun to drive as its hard-top brother, but you can’t go fast enough to find out. Because you’d arrive everywhere with tumbleweed hair, a bright red face and your eardrums on the outside of your head. That’s not a good look.

Rule one, then, when buying any of these cars is to choose the smallest possible engine because anything more is a waste of fuel. And rule two is to think very hard about the wisdom of a soft top with four seats.

I have said many times that the only person who ever managed to look good in the back of an open top car was Hitler. And maybe Mussolini. Your mates, I suspect, will look ridiculous back there, unshielded from the wind and in the full glare of other road users.

I mean it. There was a photograph published recently of the Rolling Stones driving along in some enormous American drop top from the Sixties. Up front you had Jagger and Keef and they were getting away with it. Just. But in the back Ronnie and Charlie looked absurd. And if these guys can’t pull it off then it’s for damn sure your friends from the golf club can’t either.

Yes, children like the idea of being in the back in the slipstream, and in most soft-top four-seaters they’re the only ones who’ll fit. But I can guarantee — I’ll even bet you on this — that before you’re out of your own town they’ll want the roof putting up again.

It’s like being tickled. They want you to do it, but immediately they want you to stop.

Soft-top cars, really, have to be two seaters, and that’s only because there’s no such thing as a drop head for one. It’s all about hedonism. It’s about taking the mundane chore of driving and sacrificing everything, comfort, style, and your hair, to liven it up a bit.

A bit like downloading pornography while you’re at work, then. And you wouldn’t want to share that with your friends and family, either.