Motoring: While the roofs are up, the prices are down: January may not be the time to drive a convertible, but it is the time to buy one. Steve Cropley offers a guide to the market

The snow is drifting or the rain is horizontal; the sun has gone on holiday. At this time of year, motorists are worrying about fog and ice and anti-freeze. Hardly anyone is thinking of buying a second-hand convertible. Which is why it makes sense to purchase one now.

Cars are plentiful. Dealers are pleased to see you. But most important, prices are low. Convertibles tend to hold their value much better than equivalent saloon cars, but the difference between their winter and summer prices can be several thousand pounds. Nothing will be quite so sweet next summer, as you drive along in the balmy open air, as knowing that all that motoring enjoyment came your way at a bargain price.

Michael Garrett, managing director of MJA, the Surrey-based dealer chain, specialises in off-season convertible sales. 'Our prices are keen, and we're careful to explain that it's because of the time of year,' he says. 'Soft-tops are a fashion item, at their best in summer, but we find that a surprising number of people see the sense in buying in winter.' A late-model Ford Escort 1.6i soft-top, selling at pounds 9,250 now, would cost pounds 11,000 in the summer, he says, despite being six months older. On bigger, pricier convertibles - a Saab 900 or a BMW 3-series, for instance - the savings can be even greater.

Costly insurance remains a stumbling block, however. Convertibles tend to attract higher premiums than saloons and hatchbacks of similar performance, so faster models can be very expensive to insure. But other costs need be no higher than those of a saloon car. Most convertibles are based on a well-known saloon or hatchback, so spares - and all servicing, rust- proofing and warranty details - are usually the same as the equivalent hard-top. And there is no reason why a convertible should have a shorter life than the average family car.

Over years, convertible ownership can make a lot of financial sense. A 36,000-mile, 1989 G-registration Peugeot 205 CTi, for instance, which cost about pounds 12,000 new, would be worth about pounds 6,500 next summer in a private sale. Its tin-top equivalent, the 205 GTi 1.6, which started life pounds 1,000 cheaper, would probably fetch about pounds 3,500. And when they are more than 10 years old, convertibles start appealing to classic car enthusiasts.

According to Quentin Willson, BBC-TV's Top Gear pundit and deputy editor of Car Choice magazine, winter buyers are put off by what they see as the convertible's impracticality. 'In fact,' he says, 'today's models offer near-perfect weather sealing, their heaters are powerful enough to keep the cabin snug in below-zero conditions, and even some of the cheaper ones have double roof-linings and rear window demisters.'

Besides, Willson says, on some winter days top-down motoring is perfectly feasible, provided the occupants are warmly dressed. 'A lot of motorists before the war knew no other way, and they had no heater . . .'

Nearly a dozen saloon-based convertibles are available in Britain:

Audi 80: Recently launched in Britain, so hardly any available on the second-hand market. Looks good, excellent accommodation for four, but body not very rigid and performance unimpressive.

BMW 3-series: Current model still based on the old-shape saloon (new model available in right-hand drive early next year); well-built, fun to drive, it makes a good second-hand buy, particularly the 318i (four-cylinder) or 320i (six-cylinder) versions.

Ford Escort: Good, solid all-rounder, nice to drive. Spares readily available. Two shapes, pre- and post-1989: earlier examples not as well made as the late-Eighties ones; versions badged XR3 carry high insurance premiums. Best choice: late-shape 1.6i with power hood, CD player, alloy wheels, electric windows.

Peugeot 205: Convertibles don't come prettier; designed and built at Pininfarina. Higher-performance CTi (based on GTi) easier to find, but don't dismiss sweet, soft-riding 1.4-litre CJ. Bodies durable, though they do creak and groan.

Renault 19: Recent arrival, very impressive in price and style. Not yet readily available second-hand. Insurance for quicker 1.8, 16-valve no more expensive than for saloon equivalent.

Rover 200: Compact, easy to drive, well made, relatively cheap to own. Insurance costs containable for both the 1.4- and 1.6-litre versions. Supplies just starting to reach used-car market.

Saab 900: Odd-looking, but upper models well decked out with niceties, such as power hood and auto transmission. Turbo's performance hardly necessary (attracts Porsche insurance).

Vauxhall Astra: Two models, pre- and post-1991. Earlier cars have love-it-or-hate-it styling and rather stiff suspension. Late models expensive, rare, but good. Old-shape GTEs and latest 2-litre very pricey to insure. Best buy: current shape 1.6, if you can find one.

Vauxhall Cavalier: Sold unsuccessfully in the mid-Eighties. Not very pretty; cabin too long, so rear passengers practically blown away. Hard to resell, best avoided.

Volkswagen Golf: Based on an outmoded model - still uses parts from Seventies Golf Mark I - but surprisingly nice to drive. Many versions available. Best to avoid over-ornate and fastest

Here are some hints to help you select the best:

Avoid like the plague anything that isn't a standard production model: modified cars may have leaking hoods, flexible bodies, and be prone to rot and failing the MoT.

Concentrate on low-to-middle specification cars, although a power-operated hood is worth having if it works properly. People who own them say convertibles are for cruising, not racing about, so there is no need to pay for extra power and performance.

Security: Fit a good alarm (or buy a car with one fitted), a good steering-wheel lock and a lift-out radio. Convertible insurance premiums are high because thieves find these cars easy meat.

Remember the crucial car-buying rules that apply to any purchase: make sure the person selling the car is entitled to do so; don't buy without a service history; verify the mileage by talking to the previous owner; and have the car's condition checked by experts, such as AA or RAC engineers.

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