Motoring: Wide-eyed and topless: Bitten by the convertible bug, James Ruppert set off in search of second-hand soft options

Summer may not have really arrived, but the cabriolet season is in full swing: tops are coming down, and prices in the classified ads are going up.

In an ideal world, the second-hand soft-top buyer would find a cherished, fair-weather convertible that has been kept in a heated garage and regularly serviced. Sadly, springtime flushes out a crop of unscrupulous sellers.

To avoid being caught out, make sure that any car in which you are interested has a full service history. A soft-top used only for posing purposes during the summer and ignored for the rest of the year is unlikely to have been serviced at the right intervals - which can lead to severe engine wear. Ignore the deceptively low mileage and look out for blue smoke from the exhaust, overheating and perished rubber tubing under the bonnet. Clutches will also stick open and brake discs corrode, so that, initially, braking performance will be poor.

An abused hood can be folded away, so remember to unfold it, checking its operation and looking closely at the fabric. On modern cars, hoods are costly to repair and replace. Bear in mind that seats and interior trim are likely to have been baked by the sun and soaked by rain.

With older 'classics', look beyond the gleaming paintwork and period charm at the reality. Rust is often rampant. A quick fix is filler and fresh paint. Inside, look for water stains - and lift the carpets. If possible, take the car to a garage so that you can put it up on ramps to look underneath for bodged repairs and rust. If the car has been 'restored', find out who did it and ask to see the receipts and photographic records, if any.

You might love the idea of a convertible, but your insurance company will probably take a different view. As open-tops are more vulnerable to theft and vandalism, premiums will be higher; and the wrong car in the wrong area may be prohibitively expensive. Check this out before you buy. My search for good convertibles coincided with a downpour and an unpleasant wind. This was lucky because: (1) if you can live with a damp cabrio you will adore it when the sun comes out; (2) wet weather makes it easier to check for leaking hoods; and (3) sellers are more likely to soften their soft-top prices in a gale.

The most numerous, popular and reliable open-tops are those derived from hatchbacks. At Hills Garage in Leytonstone I found a 1988 VW Golf GTi. Every bit as good as the saloon version (albeit slightly heavier and slower) this smart, businesslike little car displayed no evidence of its 50,000 mileage: unmarked grey paintwork, unchipped alloy wheels, factory-fresh interior. This was a two-owner car with full service history, at a tempting pounds 4,995. For cash I could have pushed the garage a few hundred pounds lower, although I was politely informed that when the sun shone they would have no trouble in getting pounds 5,500.

In search of something much less sensible, I took a trip to the Harlow car centre to view a 1984 Jaguar XJS 3.6 advertised at pounds 6,995. It had a 98,000 mileage, two previous owners, bubbling paintwork, a resprayed nearside wing and a patchy non-franchise service history. Which is why I thought the price ought to tumble. And it did - down to pounds 6,495 and, if I was prepared to buy direct without the added complication of a warranty, all the way to pounds 5,995.

But I could not be persuaded. In the upmarket drop-top stakes I would always plump for a stylish BMW 3-series. I popped into Hexagon of Highgate, a BMW dealer that always has at least a dozen cabriolets to choose from. At one end of the scale was a 41,000-mile 1989 320i with a leather interior for pounds 12,995. By doubling my budget and expectations, I could have had a 1992 325i, again with leather, a low 13,000 mileage, and an electric hood, all for pounds 22,995.

Not far from Stansted Airport I met Fred and his classic but more affordable pounds 950 MG Midget convertible. The last MOT had run out back in 1990, but the engine turned and the floor was solid.

Of course, an old MG comes at a fraction of the price of its modern equivalent, the Mazda MX5. Chequered Flag in Chiswick has a bewildering line-up of these Japanese cars, which created the retro style to be worn by new offerings from Alfa Romeo, Fiat and MG. There were 15 to choose from, starting at pounds 10,295 for a 1989 model, rising to pounds 15,295 for a 1992 special equipment version.

They may be pretty, easy to drive and faultlessly reliable, but I still could not afford one. So it was back to Fred and his mouldering Midget. Even though it was cloudy and cold outside I reckoned that the Midget could just be running by the autumn, so it looks as though, against all my best advice, I'll be taking on a restoration project. Please, don't try this at home. Unless you are as mad as I am.

(Photograph omitted)