An Alfa Romeo 156 - especially a blood-red one, which was the colour of the one I borrowed - seems essentially to have been designed with two things in mind: 1) going fast in order to impress people, and 2) going slightly faster in order to impress them just that little bit further. Its purpose on earth is to belt along at a knuckle-whitening pace and to go in and out of corners without slowing down, while flinging out, like so many sparks in its wake, brightly twinkling messages about its owner's taste and testosterone levels.

It is a standard jibe against the male owners of fast, blood-red cars built in Italy that they must be compensating hard for shortcomings in the genital region. It is my uneasy feeling that the Alfa 156 could be the very ruin of this trusty and much-loved old gag. It is possible that a man might buy one because he was spectacularly well-endowed.

You and I would call it a saloon; Alfa Romeo calls it a "sportwagon", which is faintly oxymoronic to the English ear, but maybe has a kind of spritz about it from a pan-European point of view. The notion, anyway, is that the 156 provides the speed-hungry driver with the punch and twitch of a sports car, while simultaneously offering the kinds of extras that a sports-car owner can only dream about, namely passenger seats, four doors and a commendably deep boot.

The instantly flattering thing about the 156, from the driver's point of view, is that the car appears to be all about you. It's interested in you, you and you, and it doesn't seem to want to talk about anyone else. In the figure-hugging cockpit, the cutely traditional circular dials and clocks are all tipped and tilted in the driver's direction - including, incidentally, the clock (a proper clock, with hands, naturally).

Which seems a bit rough on your passengers. Obviously, you don't mind them not being able to see exactly how fast you are going, especially if they happen to be of an anxious disposition. And you might even have your own obscure reasons for wanting to keep the oil and fuel levels secret. But they might be interested in knowing the time every now and again, without having to ask you to tell them.

Still, nobody ever accused Alfa Romeo of falling short on design. The car is decked out with features that have clearly grown from years of exacting work on a drawing board in Italy. The car has the kind of bonnet that seems to be urging you to behave as if you're in a cheesy advertisement and run a loving fingertip along it. It rolls down grandly into the Batmobile-style grille and it's as if the whole point of the car's front end was to provide a suitably cool setting for the Alfa badge.

Feel the quality of those door handles, too. The car comes with big, chrome push-button grips, apparently salvaged from a 50s fridge and carefully restored. Just the two of them, mind. The back doors are fitted with cunning inlaid catches, the better to con people that what you are really driving is a two-door coupe. It's part of a commitment to flushness which is mirrored in the totally button-free boot. (You pop it open using the remote or the interior lever on the floor.)

The interior has got its work cut out living up to the stylishness of the exterior, and it seems to be a bit out of breath with the effort. On the plus side, there is a lot of dark, soft-touch plastic. And the steering wheel is reassuringly thick - no bad thing given the amount of time one will spend clinging on to it for dear life. But I haven't seen so much suede since we took my eldest brother to university in the 70s. It was like sitting inside a lecturer's shoe. The hi-fi and heating console is a bit of a letdown, too; it looks like a Curry's own-brand music centre.

One other passion-killer: no cup-holders. Cup-holders may not wholly accord with Alfa Romeo's idea of sexy motoring, but they sure as hell accord with mine and with that of millions of other drivers. Maybe Alfa imagine we will be too absorbed by driving ever to need to drink at the same time. If so, they imagine wrongly.

I drove the 16v diesel version, which would, in the past, have been anathema. But these days diesel can be made to do nearly as good an impression of rocket fuel as petrol does, especially if your engine comes turbo-charged. The usual diesel chatter is very quickly consumed in the Alfa roar. It is agile in urban settings and a wasp-stung cheetah on a motorway, where the car's copious ability to accelerate from standing is, if anything, less startling than its ability to accelerate at pace, to add speed to speed.

Yesterday, I burned up to a T-junction and came to a jolting halt right in front of someone I know and the buggy containing her two children. An embarrassing and sobering moment, clearly. But it wasn't me, honest. It was the car.