Facelifts usually make old, vain people look like tight-skinned zombies. And their track record at improving the look of cars isn't much better.

Mid-life facelifting is a long-held car industry ruse to make old cars look new. A nip and tuck here, new lights and a new grille, a few new body colours, add a few hundred quid to the price, market it as "the great new etc etc" or "the new-look etc etc".

Then wait for the punters to flock to the dealers, chequebook in hand, mistakenly believing that they're buying a new model whereas - in fact - they're buying the car equivalent of a middle-aged man squeezed into Brad Pitt's 501s.

All car makers are at it, although it tends to be the mass makers who practise the art most enthusiastically. Usually, a new car has one mid- life facelift, to freshen it up, three or four years after birth, and three or four years before it is eventually pensioned off, to be replaced by an all-new model.

All-new cars usually look fine, because the stylist starts with a clean sheet. It's the old facelifted cars that normally look like motorised Nancy Reagans.

The latest lovely car, ageing gracefully, to be ruined by the stylist's scalpel is the Mazda MX-5. Born in 1989, it was responsible for the rebirth of the affordable two-seater roadster following Rover's cowardly decision to kill off MG. It was a huge success, tempting Rover quickly to dust off the MG badge and jump back into the market with the MGF. Other car makers followed. The MX-5 still looks fabulous and still sells well although, naturally, it's past its showroom peak.

You can't blame Mazda for wanting to give it a makeover, to stimulate sales. But the trouble is, once you try to "improve" the look of a classic car design, you invariably ruin it. Which is precisely what Mazda's stylists have just done to the MX-5. Those who have driven it (I haven't as yet) tell me that "the new MX-5" is actually better than the old one. It's just a shame it looks like an original MX-5 that's spent far too much time in the oven and started to melt.

Most great old cars are ruined when the redesign boys get their hands on them. The first Fiat Uno was a beautifully proportioned small car that won European Car of the Year, and replaced the old Fiat 127 as staple transport of the Italian working classes. The facelifted Uno was an ugly little thing, replete with squared-off nose and tail and ugly new grille and lights. Still with Italy: all Alfas get uglier as they get upgraded. The Spyder, the Sud, the 164 - all went from gorgeously homogeneous shapes into lovely shapes spoilt by ugly bits of plastic grafted on.

The first front-wheel-drive Ford Escort, launched in 1980, was easily the prettiest. Subsequent revisions and changes have improved the car but have usually been regressive, none more so than the most recent update, which gave the Escort the Ford-corporate goldfish nose.

And still on Ford, the styling surgeon who facelifted the Scorpio - now nicknamed the Ford Frankenstein - should put back on his flippers and goggles and go back to the fish tank whence he came. Scorpio sales have collapsed since that car got its new look. It's a pity because, underneath that giant carp exterior, the Scorpio is actually rather a good car.

The more stylistically aware car makers, of course, leave good design alone, and try to improve their ageing cars in other ways to stimulate sales. Peugeot sensibly reckoned that the 205, one of the best-looking small cars ever, was impossible visually to improve, so concentrated on revising those areas of the car (the steering, the engines, the cabin) that were substandard. The 306 was similarly updated.

Fiat recently improved the Punto but left its shape - still so progressive - alone. Rover facelifted the Mini in 1969 by squaring off the nose and tail and calling it the Clubman (although it still built the old, more characterful model alongside). The Clubman looked dreadful and died. The original, subtly altered, still soldiers on, a testament to great, unsullied design.