John Walsh: Some like it hot. Some like it topless

I wanted a PT Cruiser as soon as I saw the original adverts four years ago. Chrysler's mould-breaking family car seemed to me both terribly old-fashioned and howlingly cool

I wanted a PT Cruiser as soon as I saw the original adverts four years ago. Chrysler's mould-breaking family car seemed to me both terribly old-fashioned and howlingly cool. For one thing, it looked defiantly un-modern; that long, dignified rear door, that wrap-around radiator grille, a big, American smile like Joe E Brown's in Some Like It Hot; those recessed dashboard dials that couldn't have been more Fifties retro if they were finished in Bakelite. And lastly, that highly sprung upholstery, which made every passenger sit up as though being given a lecture on deportment by Miss Manners.

Dashingly elderly, coolly boxy, swishily cumbersome, the Cruiser was an automotive paradox. One minute you felt you were driving a getaway car in a 1952 film noir; the next you were living the bourgeois dream in a Picture Post photo-shoot ("Look - the British nuclear family motoring in the country").

Any car that bristles with so many associations acquires an instant place in your heart; but driving it was less of a love story. For all its stolidity, the PT is a little car, with little-car capacities and ambitions. Its 2.0-litre engine whines, the transmission is puddingy and it accelerates with wheezy reluctance.

Still, I bought one, and learned to love it despite its other faults, such as the intrusive head-rests and the thumping you hear (and feel) under the clutch every 100 miles or so, something no garage can explain.

I stayed with it because it's got bags of that rare commodity in modern cars: charm. It handles well, it's capacious and cosy, and all the seats fold down and awayfor shopping or picnics. In some ways, it's like driving a horizontal walk-in wardrobe. Now its brash cousin, the Cruiser Cabrio has arrived. It is a more angular, stripped-down, three-door version of the original. First impression is of weightiness: the front doors are awesomely big and heavy. The larger 2.4-litre engine purrs with a satisfying, muted growl as you glide around corners. It's a much smoother ride than I'm used to in the Cruiser; and since it is left-hand-drive with automatic transmission, I couldn't resist resting my elbow out of the window, James-Dean-style, while steering with one finger.

None of this is really the point, though. The point, as my 13-year-old son could tell you, is that this is a convertible with a 10-second roof-retracting action and a sexy overhead sports bar, apparently borrowed from a beach buggy. As we set off, with the top down in November, he let out a delighted yell of "Rock on, Dulwich!" - which is, I think, a first for London SE21.

I enjoyed it, too. Nothing beats having the whole 360-degree panorama to look at when you're reversing or parking or idling at the lights. The back-seat passengers enjoyed 10 inches' more leg-room, and I liked my first experience of navigation technology: how amusing it is to hear the female voice insisting, more shrilly each time, that you turn left now, then lapse into a silent sulk when you don't.

The only serious flaw is the boot. It's small, you have to limbo under the back door to access it, and a great steel rod cuts the space drastically. I couldn't get the shopping inside, no matter how much I tried. But what was I expecting? This is a convertible, a jolly summer ride; it's not supposed to be a Sainsbury's-visiting family saloon like the Cruiser. Which calls into question: should something as stolid and retro-serious really be cruising the streets of London with its top off?