The conversation tends to go like this: "Run that past me again: you review cars?"
"Yes."
"A different new car each week?"
"Pretty much, yes."
"And these people from the car companies, they deliver these cars to you at home?"
"Yes, they do."
"With a full tank of petrol?"
"Always."
"And then you drive the car around for a few days?"
"I do."
"And then someone comes and takes it away?"
"Yes."
"And then another new car arrives?"
"It tends to."
"Jesus."

At this point, I perform a slight shrug and a wincing smile. What can I say? They're absolutely right: motoring journalism is dangerous, lonely work. But someone's got to do it. And I'm not even on the frontline. What about the guys who are out there risking themselves, week after week, testing models at the industry launch events? Those boys are the A-force, ready to mobilise with just a couple of months' notice and deplane, all expenses paid, in some resort or another on the European mainland in order to observe how pretty a Daewoo Matiz looks coming down a Spanish mountain.

Now, those guys see some action. Sometimes the free waterproof diving watch that was saucily laid alongside the complimentary leather pochette of grooming products in the four-star hotel room ends up setting off the metal detectors at the airport on the homecoming trip. You don't want just anyone alongside you at a moment like that. You want men of steel.

Still, even we humble road-testers know what it is to graft and scrape in combat conditions and experience the all-too-human limits of our endurance. We know what it's like to face up to a seemingly unsurmountable enemy in violently hostile territory. Well, you try getting the third row of seats out of a Peugeot 807. Hell, there are some weeks when the smell of a new car is never out of my nostrils - that compelling but also slightly sickly aroma of recently installed leather and artificial shining products.

Listen to this: I once spent the best part of 20 minutes searching for a cup-holder in a Mercedes SLK200, only to discover that it didn't have one. Still think it isn't tough? And I haven't even begun to mention the parking tickets, which are a daily threat in a permit-restricted area such as my own. Do parking wardens get a special, life-enhancing kick out of ticketing brand-new, top-of-the-range cars? I have anecdotal evidence that suggests they do. They're only human, after all. Well, almost.

Much as I'd like to be humble about it, I can't pretend the job doesn't involve sacrifices. For instance, the car reviewer is denied the inalienable right of every other road-using citizen to express his or her character, consistently and over a substantial period of time, through his or her car. Rather than becoming the kind of person who drives a Vauxhall Astra for, perhaps, five or six years, the reviewer is necessarily a bigamist and opens himself up to being mistaken for the owner of pretty much everything.

Sometimes, one relaxes into the idea of the mistake: if people assumed I actually owned that BMW 7 Series, or that I had just dropped £40,000 or so on that lovely two-seater Lexus, the SC430, that once graced my drive, then I guess I was just about prepared to live with it. When, however, people raised their eyebrows at me as I stepped from a banana-yellow Suzuki Cappuccino, or crawled arthritically from what passes for a door in the Daihatsu Copen, I could only feel, as the colour flamed in my cheeks, that an urgent explanation was in order. I have spent some four years now attempting to perfect a facial expression which, when seen through a neighbouring car's windscreen, will effortlessly communicate the sentence, "It's not mine; I'm only testing it." And the closest I have got is a semi-pained look around the eyes and mouth which suggests I am trying very hard to hold on until the next available lavatory.

All in all, reviewing cars is a dizzying and potentially corrosive experience for one's sense of self - as well as being confusing for your neighbours, who see your financial fortune, as reflected in your choice of motor, fluctuate on a weekly basis and therefore assume that you are either something in the City or a drug dealer.

Quite apart from that, as you dive from one model to the next, you're forever forgetting where things go: little things such as the accelerator, the gear-shift and the brakes. There is a period following any changeover in which the reviewer drives the current car as if it were the previous one. You adjust eventually, of course - and, with any luck, before sliding the car on its roof into a bush. But I would suggest that this sensitive changeover period is the one in which the reviewer's life, and the lives of others, are most at risk.

There's no getting away from the fact that motoring journalism wouldn't be everyone's idea of a job. I suppose it's more likely to appeal to the kind of person who wonders what life would amount to if you never pushed yourself. Not that I've ever pushed myself; in the rare event of any of these virtually box-fresh cars breaking down, the company can usually be relied upon to get a spanking new one out to you within a day. The car companies tend not to mind too much about damage of any kind, in fact, as long as it's not wilfully inflicted. (Motoring journalists don't do much in the way of crash testing, preferring to leave that to the dummies. But we probably should do more. After all, it's one thing to check the capacity of the glove compartment on behalf of one's readers, quite another to inform them whether the crumple zones on an Avensis fulfil Toyota's claims for them.)

Naturally, there's a certain pressure one feels, with any entirely pristine car, to get it through the week unscathed. And when it comes to making one feel sick to the pit of one's stomach, there is nothing like damaging a new and hitherto whole car, as I learned one chilly morning in a Sainsbury's car park, when a stationary Nissan side-swiped my Fiat Multipla, and as I learned again, when another lethally parked car, this time in a narrow street, put a thin red line along the length of a £45,000 Audi A8 in which I happened to be driving past at the time.

It was with some trepidation that I phoned Audi on another occasion to let them know that a passing lorry had just removed a large part of the rear wing-section of one of their A4s while it was parked on my street. (Apparently the lorry had thought it might be simpler to drive over the car than to go around it.) Yet it was with lasting relief when I heard the person at the other end of the line become slightly nervous himself while informing me that, although another model would be with me before the afternoon was out, "it might not be the same colour."

But why wouldn't the industry be easy on its reviewers? They know the kind of pressure we're under and the fact that we're on the road, putting our balls on the line for the greater glory of the industry every day of the week, or taking our children to school, which pretty much amounts to the same thing.

Children, incidentally, are a car reviewer's handiest tool. If you want to find out how well a car's interior has been screwed together, introduce a loose three-year-old into the rear of its cabin, close the door for two minutes, and then see how many tray-tables the child comes out with. Chances are the child will be clutching all sorts of bits of plastic that you had no idea the car contained.

So why do we do it? Why would anyone put themselves through this kind of aggravation when other, simpler and less demanding jobs in journalism - such as, for instance, war correspondent - might equally have beckoned? I don't know, really. It's hard to explain, beyond that shrug and that wincing smile. You get to drive a lot of cars, though. There are consolations.

My car and me

Type 13 Bugatti, James Diffey

"I've got a 1924 Type 13 Bugatti that I use for trialling. I saw one in Wales when I was seven and it impressed me so much I decided I wanted one. I've spent 30 years looking for one and working to afford it. I finally bought it in February for £50,000. It's a super little car, even though things started to fall off it as soon as I bought it. I've spent six months restoring it and I did all the spannering myself - I'm a reasonably competent mechanic but not an engineer. If I could have any car I wanted? For racing, it would have to be a Ferrari 250 GTO. For an everyday car, I'd like a BMW 330 diesel."
James Johnson