Just in case you didn’t know, the “compact executive segment” is not a group of slim, short, high-earning business managers; in automotive-speak, the phrase describes medium-size cars of quality, performance and image. Likewise, when an American tourist exclaims: “It’s like being part of a Constable pain’ing,” he or she is not describing a police first-aid course, but is overawed by the beauty of Dedham Vale on the Essex-Suffolk border when viewed from a convertible.

The new BMW 3 Series retractable hardtop convertible is a compact executive car and the view from it — roof up or down — can make its occupants feel part of the scenery.

BMW is adept at styling convertibles and roadsters. Its 1930s 328 was a fine early example, the Mille Miglia version of which is said to have inspired the Jaguar XK120’s svelte lines; the BMW 507 two-seater of the 1950s with detachable hardtop and folding soft-top was one of the best-looking cars of its type produced — and the new 3 Series Convertible shapes up well, too.

Building convertibles is not what it used to be. Body-flexing is not allowed, the dashboard must remain rigid without a squeak or rattle, maximum passenger protection is essential in the event of a roll — and for folding hardtops such as the 3 Series, when the roof is up, the car has to be virtually indistinguishable in look and comfort from a coupé or a two-door saloon.

As expected, BMW has given its new model just about everything that a modern convertible must have, including extensive safety systems. Its metal, folding roof (de rigueur in today’s topless car world) is more akin to a piece of civil engineering than automotive design but can be opened in only 22 seconds.

Roof up, a first-time traveller in the car would probably never suspect that it was a convertible; it feels solid, sounds quiet and looks integrated. It also has 30 per cent larger rear side windows and a 38 per cent bigger rear window compared with those of the outgoing soft-top 3 Series, making for a proportionately better view of Constable country.

Roof down, the 3 Series is transformed into the next best thing to a sports car and occupants of the front seats are well protected against buffeting. Although BMW may have you believe that the convertible is a four-seater, it is more a 2+2. The backrest of the rear seat folds down to make extra luggage space and there is the option of a 40 x 26mm through-load slot into the boot to facilitate carriage of skis.

Compared with the coupé, the convertible loses 47 per cent of luggage space with the roof down, 12 per cent with it up. There is another change compared with the coupé; the SE Convertible has softer suspension. It does not detract seriously from the car’s handling, which remains beautifully balanced with a 50-50 front/rear distribution, but there were times on fast, winding roads in the twin-turbo, 302bhp 335i version when I wanted it to feel a shade sharper. The M Sport option, which includes stiffer suspension, is worth considering and is likely to prove very popular.

As always with BMW, there are several great engines from which to choose, ranging from the 2.0-L four-cylinder 320i to the 335i. With extra body stiffening, the convertible weighs about 180kg more than the coupé, but the 335i still cracks on to 62mph in 5.8sec, making pleasant noises in the process. The 325i has 215bhp, is very smooth, but not overly exciting.

There is also the powerful diesel 330d (500Nm) 228bhp, which reaches 62mph in 7sec and averages 41.5mpg, with emissions of 181g/km. More diesels are to come. Optional automatic transmission suits the six-cylinder cars, although I do not like its paddle-shift design.

Another tempting option is leather upholstery (£1,365) with “world first” technology called SunReflective. Embedded pigments reflect infra-red radiation in strong sunlight to reduce seat and armrest temperature by 20C — welcome news for the thrusting population of the compact executive segment, who at least like to be thought of as cool.

Specifications

Car BMW 335i Convertible

Engine 3.0litre six-cylinder direct injection 302bhp twin-turbo

Transmission Six-speed manual (six-speed auto optional)

Performance 0-62mph 5.8sec, top speed 155mph

Fuel consumption combined 28.5 mpg

CO2 emissions 238g/km

Price £37,930 (M Sport £40,250)

On sale Now

Alternatives: Audi A4 Understated, high quality

Mercedes-Benz CLK Practical, not very sporty

Volvo C70 Safety conscious; steady drive

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