In many ways, BMW’s 1-Series is the car that should never have been. Sticking to their rear-wheel drive guns in a market where front-wheel drive reigns supreme, the men from Munich created an oddball hatch that seemed flawed from the outset.

It looked dumpy and angular. All the extra hardware needed for the rear-wheel drive system made it heavy. And because of the rear diff and the prop shaft running from front to back, interior packaging was compromised, specifically for rear occupants.

As it turns out, none of these elements could get in the way of healthy sales, driven by brand loyalists only too glad to encounter a more affordable BMW – and yes, a “real”, rear-wheel driven one at that.

The 1-Series has since cemented its place as an upmarket hatch, and the more powerful versions have attracted many kudos for their performance and their handling.

The 1-Series Coupé and Convertible are the more glamorous cousins of the 1-Series hatchback – even though the hatch has just been replaced by an all-new, chunkier 1-Series in Europe.

However, the coupé and convertible have been retained – at least for now – and have only undergone a minor facelift, perhaps in an effort to prevent the brand new hatch from stealing all the 1-Series thunder.

The model under scrutiny here is the 135i Convertible – a car that looks deceptively innocuous, but actually packs a pretty mean punch.  With the roof raised, its silhouette looks more like a three-box sedan than the sleek shape its nomenclature suggests.

The three-box profile is dominated by a long bonnet, a steeply raked windscreen, a low roofline and that pert, rear deck. The hood is a conventional canvas roof that can be stowed or raised electrically at the push of a button.

Frankly, you’ll need to be a BMW expert to spot the differences. If you look closely, you’ll see slight changes to the design of both the headlights and the tail light clusters. There are also subtle updates to the grille, the front air dam and the air intakes, all of which conspire to create a stronger, more aggressive appearance.

But there’s also a functional aspect to these changes: BMW says airflow is better managed, allowing improved brake cooling and reducing overall drag, which in turn improves efficiency.

The new headlights are bright-white Xenon units, and feature integrated daytime running lights, while the tail lights also use LED elements.

Bottom line? The details do make a difference, but not enough for owners of pre-update cars to lose too much sleep over.

For me, one of the core attractions of the 135i is the engine. It’s a turbocharged, 3.0-litre straight six with a twin-scroll turbo, and is credited with 225kW, together with 400Nm. It’s a powerplant that always sounds muscular, but in the 135i it has an even more wicked engine note than usual.

The engine can be matched to a six-speed manual gearbox, or, as is the case here, to a seven-speed dual-clutch transmission with what BMW calls Sport Automatic shifting. It’s not as incisive as the M3’s M-DCT gearbox, but shifts are still very rapid and seamless, and shift paddles are provided behind the steering wheel.

Of course, the 135i is rear-wheel driven in the best BMW tradition. And talking of tradition, the convertible roof is a fabric hood, rather than the metal folding type which has become so popular.

A canvas hood may not have quite the same visual elegance as a metal roof, but it is much lighter, much simpler, and much quicker to raise or lower – a process that, by the way, happens electrically at the push of a button. Plus, it has far less impact on luggage space.

The update has also entailed a number of small tweaks to the interior, aimed mainly at emphasising interior comfort and elegance. The range of trim and upholstery options has been extended to allow even greater personalisation than before. And the switchgear has been improved too.

Good news, though, is that the electrically adjustable seats are perfectly shaped for comfort and support. BMW remains a master of the ergonomic art, and that’s certainly the case here, while the standard equipment list is impressively comprehensive.

The picture is a lot less rosy for rear passengers. The sculpted seating positions look comfortable enough – until you realise that there’s virtually no legroom  to speak of. And the boot will cope with two or three small, soft bags – but no more.

Whatever the criticisms, there’s one facet of the 135i Convertible that overrides any negatives: the dynamic talent. And on that level, it shines very brightly indeed. All that power is only the start: it’s how the car applies the urge that really sets it apart.

For a convertible, handling is exemplary. The strut-based front suspension and multi-link rear configuration allow for nimble, confidence-inspiring road manners, while scuttle shake is really only noticeable on poor surfaces.

Stability and traction control provide a safety net without robbing the BMW of its athletic demeanour. And the brakes are excellent, with ample modulation scope and incisive stopping power.

For the statistics boffins, the zero-to-100 acceleration time comes to 5.5 seconds – 0.1sec quicker than the manual-gearbox model – while top speed is again restricted to 250km/h. Impressive? Yes – but you can also tootle along at 60km/h in sixth gear, with the engine hardly ticking over.

Of course, there is a price to pay for drop-top glamour. At speed, with the hood in place, noise levels are higher than expected. Drop the top, and wind noise becomes wind roar at anything above 100km/h. But heck – that’s the essence of convertible motoring, after all.

The changes to this latest, updated 1-Series Convertible can hardly be described as ground-breaking. Instead, they serve as a reminder of how good the car really is. As is so often the case, the best examples only start emerging halfway through the model’s life cycle and that’s certainly the case here.

Top up or down, the 135i Convertible is much more of a driver’s car than you’d expect. All the more’s the pity that, to most, it will remain a poser’s pleasure, rather than the road-going rocketship it really is. DM

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KEY STATS

BMW 135i Convertible AT

Engine

In-line six-cylinder, 2,979cc, turbocharged

Gearbox

Seven-speed Sport Auto dual-clutch

Power

225kW @ 5,800rpm

Torque

400Nm @ 1,300 – 5,000rpm

0-100 km/h

5.5 sec

Top speed

250km/h (governed)

Fuel consumption

9.3/100 km (tested)

CO2 emissions

216g/km

Retail price

R537,200  (before options)