The peacock butterfly is officially one of the first signs of spring. But those who find spotting butterflies tricky should try looking for a BMW 3-series convertible instead.

It, too, starts to appear during April and can be seen cruising country roads in reasonable numbers.

If you think I’m being flippant, ask yourself where all the 3-series soft tops go in the winter. The answer is that they trundle around with the roofs up looking pretty nondescript, but show them a bit of sunshine and they bloom into a much prettier form. And looking pretty with the roof down is just about the most important thing a convertible can do.

Serious drivers dislike them because they aren’t as rigid as a coupé, rear-seat passengers complain because there’s less legroom than in a saloon and virtually everyone moans because most of the boot space is taken up storing the soft-top roof.

But the reason for buying a convertible should never be practicality, it should be raw emotion, because if you buy a good one it will turn an ordinary journey into a special event.

And in the world of four-seater convertibles the BMW 3-series is something of the daddy. The most recent incarnation was introduced in summer 2000. The list was headed by a 3 litre 231bhp model and there were also a 2 litre, 2.3 litre and 2.5 litre.

All are smooth straight-six engines but only the 2.5 and 3 litre can really live up to BMW’s “ultimate driving machine” boast. In September 2001 a four-cylinder engine joined the line-up, badged 318.

All models are available with automatic or manual transmission. There is also a Sport model, which comes with larger alloy wheels, lower and firmer suspension and some body styling additions.

The Sport interior includes an M-Tech sports steering wheel and sports seats that are a combination of leather and Alcantara, ideally suited to holding you firmly if you decide to sling the car through a sharp bend.

While the extra features of the Sport may appeal, it’s worth driving one before you commit: in town and on poor surfaces the wheels and suspension make for a fairly rough ride. And with the non Sport models not slouching through the bends and being noticeably more supple, many owners have sacrificed looks for comfort. But for me you can’t beat the Sport.

In common with the rest of the BMW range the 3-series convertible is available in a range of colours, trims and wheel options. The most desirable cars are those with dark exteriors and light interiors, or light exteriors and dark interiors. Combine dark with dark and the car’s detailing can be lost. A light car may look good in the bright sunshine of California but can look a bit washed-out in our thin light.

Buying the latest generation 3-series convertible should be relatively risk-free and once you’ve set your budget the task should be viewed as fun.

But as average mileages climb, buyers need to be wary of the classic weak points in a convertible; electric roof mechanisms must work smoothly and without hesitation, air-conditioning should switch from pumping hot air to cold in a matter of seconds, and the upholstery — on display when you leave the roof down — should be spotless.

Roof Fully electric folding roof works beautifully and provides excellent levels of sound and heat insulation

Air-conditioning Standard feature on all convertibles produced since June 2000

Engine Base model 318 comes with 2 litre engine, the more powerful six-cylinder units are ultra smooth but real performance doesnÕt introduce itself below the 325 and 330 models

Traction control BMW's Cornering Brake Control system applies brakes if the car enters a corner too fast

Build date Check when the car was built by looking on the label attached to the front nearside wheelarch under the bonnet

Servicing Variable servicing interval dependent on driving conditions can extend service interval to 15,000 miles

Rear seat No centre lapbelt means this is a 2+2 seater only

Boot space 260 litres isn't bad for a convertible but it's still less than a Ford Fiesta

Front suspension Check for wear of the front suspension ball joints and wishbones as these are a known weak spot. This is a particularly relevant check if the car is still under the manufacturer's warranty

Sport models Larger alloys, revised suspension and sports interior trim set these cars apart, but on the downside ride comfort is compromised

The one to buy

BMW 330Ci Sport convertible 2002 02-reg with 20,000 miles. Pay £25,000 from a main BMW dealer with minimum 12 months’ warranty or £23,500 privately

Or for similar money

1999 T-reg Jaguar XKR auto
2002 02-reg Porsche Boxster 2.7
2002 52-reg Mercedes CLK 320 Avantgarde
203 03-reg Audi A4 3.0 quattro Sport
2004 04-reg Saab 9.3 2.0t Aero

Vital statistics

Model BMW 330Ci Sport convertible
Engine Six-cylinder, 2979cc
Power 231bhp
Transmission Five-speed manual
Fuel 29.4mpg (combined cycle)
Acceleration 0-62mph: 6.9sec
Top speed 53mph

Values: BMW 330C1 Sport convertible



Source: estimates based on confidential CAP black book prices. 'Trade' is what a dealer would pay to buy your car; 'Retail' is what you would pay a dealer